Update errorproneVersion to v2.31.0 (#277)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

build.gradle

@@ -21,7 +21,7 @@ repositories {
   maven { url 'https://oss.sonatype.org/content/repositories/snapshots/' }
 }
 
-ext.errorproneVersion = '2.30.0'
+ext.errorproneVersion = '2.31.0'
 
 dependencies {
   compileOnly "com.google.errorprone:error_prone_annotations:${errorproneVersion}"