chore: regenerate README (#819)

This PR was generated using Autosynth. 🌈


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

```
2021-08-27 15:02:59,147 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-pubsub/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-08-27 15:03:00,379 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/a16c954c-99b1-44c1-9c07-24e8d8d6e344/targets

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Author: yoshi-automation

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-pubsub.git",
-        "sha": "23c70fbfbea02e03fd7444ff8435096fd0bf4944"
+        "sha": "59a580f17b8ec361abbc5fe54aad70422b81e188"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "8032ab5a32471d85ece8fc261df16cc40fbfa4fb"
+        "sha": "31728d872f50e439ded2f67fa8d67955b26a4e35"
       }
     }
   ]

README.md

@@ -19,7 +19,7 @@ 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>21.0.0</version>
+      <version>22.0.0</version>
       <type>pom</type>
       <scope>import</scope>
     </dependency>
@@ -51,20 +51,20 @@ If you are using Maven without BOM, add this to your dependencies:
 If you are using Gradle 5.x or later, add this to your dependencies
 
 ```Groovy
-implementation platform('com.google.cloud:libraries-bom:21.0.0')
+implementation platform('com.google.cloud:libraries-bom:22.0.0')
 
 compile 'com.google.cloud:google-cloud-pubsub'
 ```
 If you are using Gradle without BOM, add this to your dependencies
 
 ```Groovy
-compile 'com.google.cloud:google-cloud-pubsub:1.114.1'
+compile 'com.google.cloud:google-cloud-pubsub:1.114.2'
 ```
 
 If you are using SBT, add this to your dependencies
 
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-pubsub" % "1.114.1"
+libraryDependencies += "com.google.cloud" % "google-cloud-pubsub" % "1.114.2"
 ```
 
 ## Authentication