Updating coveragerc omit section for namespace collisions.

In particular, omitting "google.cloud.logging.v2" and
"google.cloud.pubsub.v1" since they are in our "google.cloud" namespace
package but are not owned by us.

Author: dhermes

.coveragerc

@@ -1,13 +1,13 @@
 [run]
 branch = True
 
-[report]
-fail_under = 100
-show_missing = True
-
 [report]
 omit =
     */_generated/*.py
+    # Packages in the "google.cloud" package that we don't own.
+    */google/cloud/logging/v2/*
+    */google/cloud/pubsub/v1/*
+fail_under = 100
 show_missing = True
 exclude_lines =
     # Re-enable the standard pragma