chore: regenerate README (#869)

This PR was generated using Autosynth. 🌈


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

```
2020-10-26 08:35:47,512 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-bigquery/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-10-26 08:35:48,520 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/670ebb44-b396-4c53-84ea-6ab95062680a/targets

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

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-bigquery.git",
-        "sha": "80ef0072687a8f107768c65c8788b70a8a002dfd"
+        "sha": "730c023ccf78575162fb7bc2cb1820e6bb7c5449"
       }
     },
     {

README.md

@@ -40,7 +40,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-bigquery</artifactId>
-  <version>1.123.1</version>
+  <version>1.123.2</version>
 </dependency>
 
 ```