chore: add releaseType to config (#6290)
chore: add releaseType to config (#6290)

This setting is not read from the manifest config today so it is best for us to set it here for now as well. This guidance was given in https://github.com/googleapis/repo-automation-bots/issues/4032

Fixes: #5964
googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go,googleapis/google-cloud-go