chore: regenerate README (#460)

This PR was generated using Autosynth. 🌈


<details><summary>Log from Synthtool</summary>

```
2020-10-23 18:00:28,607 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigquerydatatransfer/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-10-23 18:00:29,558 synthtool [DEBUG] > Wrote metadata to .github/readme/synth.metadata/synth.metadata.

```
</details>

Full log will be available here:
https://source.cloud.google.com/results/invocations/803a80f4-c62d-40b2-a441-55bb3d2b9fba/targets

- [ ] To automatically regenerate this PR, check this box.

.github/readme/synth.metadata/synth.metadata

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-bigquerydatatransfer.git",
-        "sha": "12f9c2c16190c765c81d6fe72bd761e017219ba3"
+        "sha": "4ac277855d8062cc7432d9bf3a4d3dcc35e35c09"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "5f6ef0ec5501d33c4667885b37a7685a30d41a76"
+        "sha": "721a7d2abb129029eca9d85a40da6eb7b8b1739a"
       }
     }
   ]

README.md

@@ -17,7 +17,7 @@ If you are using Maven with [BOM][libraries-bom], add this to your pom.xml file
     <dependency>
       <groupId>com.google.cloud</groupId>
       <artifactId>libraries-bom</artifactId>
-      <version>13.1.0</version>
+      <version>13.2.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>