ResourceManager: Cleanup unused dependencies (googleapis#5689)

Author: athakor

google-cloud-clients/google-cloud-resourcemanager/pom.xml

@@ -18,10 +18,6 @@
     <site.installationModule>google-cloud-resourcemanager</site.installationModule>
   </properties>
   <dependencies>
-    <dependency>
-      <groupId>${project.groupId}</groupId>
-      <artifactId>google-cloud-core</artifactId>
-    </dependency>
     <dependency>
       <groupId>${project.groupId}</groupId>
       <artifactId>google-cloud-core-http</artifactId>