chore: regenerate README (#767)

This PR was generated using Autosynth. 🌈


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

```
2021-08-10 03:53:28,503 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-pubsub/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-08-10 03:53:29,704 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/38b1dd3c-7f3d-472f-ba31-f947a95784aa/targets

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-pubsub.git",
-        "sha": "7f94d7cc1ef92e4c7cac37ffb257f3e4f0a19a36"
+        "sha": "18d0b6964b4a5f9216040cc668cce9d54a10a37f"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "3d32990b6f4b57be77455e3ca89e6e21cd0c06b3"
+        "sha": "6252f2cd074c38f37b44abe5e96d128733eb1b61"
       }
     }
   ]

README.md

@@ -43,7 +43,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-pubsub</artifactId>
-  <version>1.113.5</version>
+  <version>1.113.6</version>
 </dependency>
 
 ```
@@ -58,13 +58,13 @@ 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:1.113.5'
+compile 'com.google.cloud:google-cloud-pubsub:1.113.6'
 ```
 
 If you are using SBT, add this to your dependencies
 
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-pubsub" % "1.113.5"
+libraryDependencies += "com.google.cloud" % "google-cloud-pubsub" % "1.113.6"
 ```
 
 ## Authentication