Release 1.6.0 (googleapis#8623)

Release firestore 1.3.0 (googleapis#8625)

* Release 1.3.0

Release 0.38.0 (googleapis#8621)

Release 0.12.0 (googleapis#8624)

Release 0.2.0 (googleapis#8622)

Release 1.16.0 (googleapis#8548)

Release 1.1.0 (googleapis#8496)

Release 1.1.0 (googleapis#8492)

Release 0.3.0 (googleapis#8457)

Release api_core 1.13.0 (googleapis#8469)