deps: auth library version should be handled by shared-dependencies import

Author: chingor13

google-cloud-monitoring/pom.xml

@@ -79,7 +79,6 @@
     <dependency>
       <groupId>com.google.auth</groupId>
       <artifactId>google-auth-library-oauth2-http</artifactId>
-      <version>0.20.0</version>
       <scope>test</scope>
     </dependency>
     <!-- Need testing utility classes for generated gRPC clients tests -->