chore: regenerate README (#629)

This PR was generated using Autosynth. 🌈


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

```
2021-08-11 21:20:45,357 synthtool [DEBUG] > Executing /root/.cache/synthtool/java-errorreporting/.github/readme/synth.py.
On branch autosynth-readme
nothing to commit, working tree clean
2021-08-11 21:20:46,582 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/39b317e8-e5fe-4713-ac47-b043b2e7458c/targets

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

@@ -4,14 +4,14 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/java-errorreporting.git",
-        "sha": "211ee0f2d096fce5b9faacfdbccb85dced2ce90d"
+        "sha": "c522d9295182360063f0bc8796afe856afbfbc91"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "6252f2cd074c38f37b44abe5e96d128733eb1b61"
+        "sha": "7e1f6da50524b5d98eb67adbf6dd0805df54233d"
       }
     }
   ]

README.md

@@ -63,7 +63,7 @@ If you are using Maven without BOM, add this to your dependencies:
 <dependency>
   <groupId>com.google.cloud</groupId>
   <artifactId>google-cloud-errorreporting</artifactId>
-  <version>0.121.6-beta</version>
+  <version>0.122.0-beta</version>
 </dependency>
 
 ```
@@ -78,13 +78,13 @@ compile 'com.google.cloud:google-cloud-errorreporting'
 If you are using Gradle without BOM, add this to your dependencies
 
 ```Groovy
-compile 'com.google.cloud:google-cloud-errorreporting:0.121.6-beta'
+compile 'com.google.cloud:google-cloud-errorreporting:0.122.0-beta'
 ```
 
 If you are using SBT, add this to your dependencies
 
 ```Scala
-libraryDependencies += "com.google.cloud" % "google-cloud-errorreporting" % "0.121.6-beta"
+libraryDependencies += "com.google.cloud" % "google-cloud-errorreporting" % "0.122.0-beta"
 ```
 
 ## Authentication