Bumped version to 8.8.0 (firebase#707)

Bumped version to 8.7.0 (firebase#692)

Bumped version to 8.6.1 (firebase#671)

Bumped version to 8.6.0 (firebase#654)

Bumped version to 8.5.0 (firebase#641)

Bumped version to 8.4.0 (firebase#627)

Bumped version to 8.3.0 (firebase#603)

Bumped version to 8.2.0 (firebase#574)

Bumped version to 8.1.0 (firebase#562)

Bumped version to 8.0.0 (firebase#538)