Add AppCheckCore version increase to CHANGELOG (google#455)

Update to beta version in Package.swift and .podspec

Prepare for Firebase App Check EAP release (google#352)

Update to Swift 5 in GoogleSignInSwiftSupport.podspec (google#317)

Bump GSI version to 6.2.3 (google#199)

Update notification syntax (google#156)

Content updates for the 6.2.0 release (google#119)

* Add 6.2.0 section to changelog.

* Add macOS support detail to readme.

* Update README.md

* Update CHANGELOG.md

Avoid implicit retention warning. (google#81)

Prep 6.0.2 release (google#54)

* Update changelog for 6.0.2 release.

* Bump version for 6.0.2 release.

Prep 6.0.1 release (google#34)

* Update changelog for 6.0.1 release.

* Update Podspec and SPM version strings for 6.0.1 release.

* Improve docs for addScopes.

* Update 6.0.1 release date.

* Add link to related pull request.

* Fix formatting.