Use google.api instead of custom googleapi package

Use the standard google.api package to not create conflicts with other
proto definition that uses the same package.

Change-Id: Ic66a0a1a0f1e68c95fd94f443112ee4fb8b1bad5
diff --git a/requirements.txt b/requirements.txt
index 3478295..9762cfa 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,3 +6,4 @@
 psycopg2-binary~=2.8.2
 pytz~=2019.1
 semver~=2.8.1
+googleapis-common-protos~=1.51.0