[chore] Release 11.9.0 (firebase#2196)

- Release 11.9.0

[chore] Release 11.8.0 (firebase#2175)

[chore] Release 11.7.0 (firebase#2158)

- Release 11.7.0

[chore] Release 11.6.0 (firebase#2139)

- Release 11.6.0

[chore] Release 11.5.0 (firebase#2049)

[chore] Release 11.4.1 (firebase#2026)

[chore] Release 11.4.0 (firebase#2015)

[chore] Release 11.3.0 (firebase#1981)

- Includes the new `extensions` API

[chore] Release 11.2.1 (firebase#1972)

[chore] Release 11.2.0 (firebase#1942)