[chore] Release 6.13.0 take 4 (firebase#416) 

[maven-release-plugin] copy for tag v6.12.2 

[maven-release-plugin] copy for tag v6.12.1 

[maven-release-plugin] copy for tag v6.12.0 

[maven-release-plugin] copy for tag v6.11.0 

[maven-release-plugin] copy for tag v6.10.0 

[maven-release-plugin] copy for tag v6.9.0 

[maven-release-plugin] copy for tag v6.8.1 

[maven-release-plugin] copy for tag v6.8.0 

[maven-release-plugin] copy for tag v6.7.0