Bump com.uber.nullaway:nullaway in the development-dependencies group (#3828)

Bumps the development-dependencies group with 1 update: [com.uber.nullaway:nullaway](https://github.com/uber/NullAway).


Updates `com.uber.nullaway:nullaway` from 0.12.4 to 0.12.6
- [Release notes](https://github.com/uber/NullAway/releases)
- [Changelog](https://github.com/uber/NullAway/blob/master/CHANGELOG.md)
- [Commits](uber/NullAway@v0.12.4...v0.12.6)

---
updated-dependencies:
- dependency-name: com.uber.nullaway:nullaway
  dependency-type: direct:production
  update-type: version-update:semver-patch
  dependency-group: development-dependencies
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

Diff for: build.gradle

@@ -187,7 +187,7 @@ configure(javaProjects) { subproject ->
 		testImplementation "org.hamcrest:hamcrest-core:$hamcrestVersion"
 		optionalApi "org.assertj:assertj-core:$assertjVersion"
 
-		errorprone 'com.uber.nullaway:nullaway:0.12.4'
+		errorprone 'com.uber.nullaway:nullaway:0.12.6'
 		errorprone 'com.google.errorprone:error_prone_core:2.36.0'
 	}