chore: regenerate README (#479)

This PR was generated using Autosynth. 🌈


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

```
2021-01-07 22:21:48,035 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-pubsub/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-01-07 22:21:48,981 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/2cffbaac-9009-4e88-b999-c46206867bfd/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": "03c3564a05ff0f087019424592a108b5688b52e7"
+        "sha": "09e086c492d492df4d4ae6bdc5f9fdea45e5fffa"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "41a4e56982620d3edcf110d76f4fcdfdec471ac8"
+        "sha": "67f09bf301083798e7220137723222eb00b8f88a"
       }
     }
   ]

README.md

@@ -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>1.110.1</version>
+  <version>1.110.3</version>
 </dependency>
 
 ```