chore: regenerate README (#689)

This PR was generated using Autosynth. 🌈


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

```
2021-06-02 20:14:17,782 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-pubsub/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-06-02 20:14:19,064 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/29792094-4795-4eba-ab91-0f7113075354/targets

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

@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-pubsub.git",
-        "sha": "68170fbcba83cf5937fd56b744b2187a34103182"
+        "sha": "9a078f1cfe272fdfe08abd380410b07923c6f101"
       }
     },
     {

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-pubsub</artifactId>
-  <version>1.112.3</version>
+  <version>1.113.0</version>
 </dependency>
 
 ```
@@ -53,12 +53,12 @@ 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:1.111.2'
+compile 'com.google.cloud:google-cloud-pubsub:1.113.0'
 ```
 
 If you are using SBT, add this to your dependencies
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-pubsub" % "1.111.2"
+libraryDependencies += "com.google.cloud" % "google-cloud-pubsub" % "1.113.0"
 ```
 
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