Update version to 0.13.0
Bump version to 0.13.0rc2.
Prepare for 0.13.0rc1 release, fixing run_executor script. PiperOrigin-RevId: 245489783
Correct release doc typo. PiperOrigin-RevId: 245347587
Releasing version 0.12.0
Releasing version 0.12.0rc3