chore: allow releases on previous major versions (#134)

* chore: allow releases on previous major versions

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

packages/google-cloud-binary-authorization/.github/release-please.yml

@@ -1,2 +1,8 @@
 releaseType: python
 handleGHRelease: true
+# NOTE: this section is generated by synthtool.languages.python
+# See https://github.com/googleapis/synthtool/blob/master/synthtool/languages/python.py
+branches:
+- branch: v0
+ handleGHRelease: true
+ releaseType: python

packages/google-cloud-binary-authorization/owlbot.py

@@ -77,4 +77,6 @@
  excludes=[".coveragerc"], # the microgenerator has a good coveragerc file
 )
 
+python.configure_previous_major_version_branches()
+
 s.shell.run(["nox", "-s", "blacken"], hide_output=False)