chore: regenerate README (#272)

This PR was generated using Autosynth. 🌈


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

```
2020-10-20 22:59:57,661 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-tasks/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-10-20 22:59:58,594 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/a11d8bb6-dd42-43b9-99b4-16c061295628/targets

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

Author: yoshi-automation

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-tasks.git",
-        "sha": "1ccdc63f1803e9d71ede05aea157be9791acbee0"
+        "sha": "c63f41352bfdaa45119c14dec76021e2ac21e8a4"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "5a506ec8765cc04f7e29f888b8e9b257d9a7ae11"
+        "sha": "6abb59097be84599a1d6091fe534a49e5c5cf948"
       }
     }
   ]

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>12.1.0</version>
+      <version>13.0.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>