Bump error_prone_annotations from 2.19.1 to 2.20.0 (#2421)

Bumps [error_prone_annotations](https://github.com/google/error-prone) from 2.19.1 to 2.20.0.
- [Release notes](https://github.com/google/error-prone/releases)
- [Commits](https://github.com/google/error-prone/compare/v2.19.1...v2.20.0)

---
updated-dependencies:
- dependency-name: com.google.errorprone:error_prone_annotations
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Éamonn McManus <emcmanus@google.com>

gson/pom.xml

@@ -46,7 +46,7 @@
     <dependency>
       <groupId>com.google.errorprone</groupId>
       <artifactId>error_prone_annotations</artifactId>
-      <version>2.19.1</version>
+      <version>2.20.0</version>
     </dependency>
 
     <dependency>