deps: update dependency com.google.errorprone:error_prone_annotations to v2.8.1 (googleapis#1420)

Author: renovate-bot

pom.xml

@@ -125,7 +125,7 @@
       <dependency>
         <groupId>com.google.errorprone</groupId>
         <artifactId>error_prone_annotations</artifactId>
-        <version>2.8.0</version>
+        <version>2.8.1</version>
       </dependency>
       <dependency>
         <groupId>com.google.appengine</groupId>