chore: regenerate README (#412)

This PR was generated using Autosynth. 🌈


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

```
2020-10-30 21:27:05,641 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-pubsub/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working directory clean
2020-10-30 21:27:06,615 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/a02c1284-94c8-4054-a1b9-92b7f5b32619/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-pubsub.git",
-        "sha": "7a1ffe0907da54c2a79a4407850a166e72af45bc"
+        "sha": "d4115871c7ad9f9168f6c144264ec96e210a9857"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "901ddd44e9ef7887ee681b9183bbdea99437fdcc"
+        "sha": "b19b401571e77192f8dd38eab5fb2300a0de9324"
       }
     }
   ]

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>13.3.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>
@@ -38,7 +38,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-pubsub</artifactId>
-  <version>1.108.3</version>
+  <version>1.108.6</version>
 </dependency>
 
 ```