deps: update dependency com.google.cloud:google-cloud-spanner-bom to …

…v1.53.0 (#562)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| [com.google.cloud:google-cloud-spanner-bom](https://togithub.com/googleapis/java-spanner) | minor | `1.52.0` -> `1.53.0` |

---

### Release Notes

<details>
<summary>googleapis/java-spanner</summary>

### [`v1.53.0`](https://togithub.com/googleapis/java-spanner/blob/master/CHANGELOG.md#&#8203;1530-httpswwwgithubcomgoogleapisjava-spannercomparev1520v1530-2020-04-22)

[Compare Source](https://togithub.com/googleapis/java-spanner/compare/v1.52.0...v1.53.0)

##### Features

-   optimize maintainer to let sessions be GC'ed instead of deleted ([#&#8203;135](https://www.github.com/googleapis/java-spanner/issues/135)) ([d65747c](https://www.github.com/googleapis/java-spanner/commit/d65747cbc704508f6f1bcef6eea53aa411d42ee2))

##### Bug Fixes

-   assign unique id's per test case ([#&#8203;129](https://www.github.com/googleapis/java-spanner/issues/129)) ([a553b6d](https://www.github.com/googleapis/java-spanner/commit/a553b6d48c4f5ee2d0583e5b825d73a85f06216e))
-   check for not null input for Id classes ([#&#8203;159](https://www.github.com/googleapis/java-spanner/issues/159)) ([ecf5826](https://www.github.com/googleapis/java-spanner/commit/ecf582670818f32e85f534ec400d0b8d31cf9ca6)), closes [#&#8203;145](https://www.github.com/googleapis/java-spanner/issues/145)
-   clean up test instance if creation failed ([#&#8203;162](https://www.github.com/googleapis/java-spanner/issues/162)) ([ff571e1](https://www.github.com/googleapis/java-spanner/commit/ff571e16a45fbce692d9bb172749ff15fafe7a9c))
-   fix flaky test and remove warnings ([#&#8203;153](https://www.github.com/googleapis/java-spanner/issues/153)) ([d534e35](https://www.github.com/googleapis/java-spanner/commit/d534e350346b0c9ab8057ede36bc3aac473c0b06)), closes [#&#8203;146](https://www.github.com/googleapis/java-spanner/issues/146)
-   increase test timeout and remove warnings ([#&#8203;160](https://www.github.com/googleapis/java-spanner/issues/160)) ([63a6bd8](https://www.github.com/googleapis/java-spanner/commit/63a6bd8be08a56d002f58bc2cdb2856ad0dc5fa3)), closes [#&#8203;158](https://www.github.com/googleapis/java-spanner/issues/158)
-   retry non-idempotent long-running RPCs ([#&#8203;141](https://www.github.com/googleapis/java-spanner/issues/141)) ([4669c02](https://www.github.com/googleapis/java-spanner/commit/4669c02a24e0f7b1d53c9edf5ab7b146b4116960))
-   retry restore if blocked by pending restore ([#&#8203;119](https://www.github.com/googleapis/java-spanner/issues/119)) ([220653d](https://www.github.com/googleapis/java-spanner/commit/220653d8e25c518d0df447bf777a7fcbf04a01ca)), closes [#&#8203;118](https://www.github.com/googleapis/java-spanner/issues/118)
-   StatementParser did not accept multiple query hints ([#&#8203;170](https://www.github.com/googleapis/java-spanner/issues/170)) ([ef41a6e](https://www.github.com/googleapis/java-spanner/commit/ef41a6e503f218c00c16914aa9c1433d9b26db13)), closes [#&#8203;163](https://www.github.com/googleapis/java-spanner/issues/163)
-   wait for initialization to finish before test ([#&#8203;161](https://www.github.com/googleapis/java-spanner/issues/161)) ([fe434ff](https://www.github.com/googleapis/java-spanner/commit/fe434ff7068b4b618e70379c224e1c5ab88f6ba1)), closes [#&#8203;146](https://www.github.com/googleapis/java-spanner/issues/146)

##### Performance Improvements

-   increase sessions in the pool in batches ([#&#8203;134](https://www.github.com/googleapis/java-spanner/issues/134)) ([9e5a1cd](https://www.github.com/googleapis/java-spanner/commit/9e5a1cdaacf71147b67681861f063c3276705f44))
-   prepare sessions with r/w tx in-process ([#&#8203;152](https://www.github.com/googleapis/java-spanner/issues/152)) ([2db27ce](https://www.github.com/googleapis/java-spanner/commit/2db27ce048efafaa3c28b097de33518747011465)), closes [#&#8203;151](https://www.github.com/googleapis/java-spanner/issues/151)

##### Dependencies

-   update core dependencies ([#&#8203;109](https://www.github.com/googleapis/java-spanner/issues/109)) ([5753f1f](https://www.github.com/googleapis/java-spanner/commit/5753f1f4fed83df87262404f7a7ba7eedcd366cb))
-   update core dependencies ([#&#8203;132](https://www.github.com/googleapis/java-spanner/issues/132)) ([77c1558](https://www.github.com/googleapis/java-spanner/commit/77c1558652ee00e529674ac3a2dcf3210ef049fa))
-   update dependency com.google.api:api-common to v1.9.0 ([#&#8203;127](https://www.github.com/googleapis/java-spanner/issues/127)) ([b2c744f](https://www.github.com/googleapis/java-spanner/commit/b2c744f01a4d5a8981df5ff900f3536c83265a61))
-   update dependency com.google.guava:guava-bom to v29 ([#&#8203;147](https://www.github.com/googleapis/java-spanner/issues/147)) ([3fe3ae0](https://www.github.com/googleapis/java-spanner/commit/3fe3ae02376af552564c93c766f562d6454b7ac1))
-   update dependency io.grpc:grpc-bom to v1.29.0 ([#&#8203;164](https://www.github.com/googleapis/java-spanner/issues/164)) ([2d2ce5c](https://www.github.com/googleapis/java-spanner/commit/2d2ce5ce4dc8f410ec671e542e144d47f39ab40b))
-   update dependency org.threeten:threetenbp to v1.4.3 ([#&#8203;120](https://www.github.com/googleapis/java-spanner/issues/120)) ([49d1abc](https://www.github.com/googleapis/java-spanner/commit/49d1abcb6c9c48762dcf0fe1466ab107bf67146b))

</details>

---

### Renovate configuration

:date: **Schedule**: At any time (no schedule defined).

:vertical_traffic_light: **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

:recycle: **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

:no_bell: **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

---

This PR has been generated by [WhiteSource Renovate](https://renovate.whitesourcesoftware.com). View repository job log [here](https://app.renovatebot.com/dashboard#googleapis/java-cloud-bom).

pom.xml

@@ -533,7 +533,7 @@
       <dependency>
         <groupId>com.google.cloud</groupId>
         <artifactId>google-cloud-spanner-bom</artifactId>
-        <version>1.52.0</version>
+        <version>1.53.0</version>
         <type>pom</type>
         <scope>import</scope>
       </dependency>