Update auth version (#621)

fix #620

Author: elharo

build.gradle

@@ -28,7 +28,7 @@ project.version = "1.35.1-SNAPSHOT" // {x-version-update:gax:current}
 ext {
   grpcVersion = '1.16.1'
   commonProtosVersion = '1.12.0'
-  authVersion = '0.11.0'
+  authVersion = '0.12.0'
   // Project names not used for release
   nonReleaseProjects = ['benchmark']
   // Project names not using the default publication configuration