Upgrade to error-prone 2.0.5

Release notes:

https://groups.google.com/d/msg/error-prone-announce/vHvZx2MOpvg/xwYSH3i6AQAJ

pom.xml

@@ -110,12 +110,12 @@
           <dependency>
             <groupId>org.codehaus.plexus</groupId>
             <artifactId>plexus-compiler-javac-errorprone</artifactId>
-            <version>2.5</version>
+            <version>2.6</version>
           </dependency>
           <dependency>
             <groupId>com.google.errorprone</groupId>
             <artifactId>error_prone_core</artifactId>
-            <version>2.0.4</version>
+            <version>2.0.5</version>
           </dependency>
         </dependencies>
       </plugin>