Bumped version to 6.4.0 (firebase#419)

Bumped version to 6.3.0 (firebase#399)

* Bumped version to 6.3.0

* Updated changelog

Bumped version to 6.2.0 (firebase#392)

bump version to 6.1.0 (firebase#375)

* bump version to 6.1.0

* update changelog to include firestore version bump

Bumped version to 6.0.0 (firebase#333)

Bumped version to 5.13.1 (firebase#316)

* Bumped version to 5.13.1

* Updated changelog

Bumped version to 5.13.0 (firebase#307)

Bumped version to 5.12.1 (firebase#269)

Bumped version to 5.12.0 (firebase#249)

Bumped version to 5.11.0 (firebase#232)