chore: allow releases from previous major versions (#708)

* chore: allow releases from previous major versions

* 🦉 Updates from OwlBot post-processor

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

* chore: add config to owlbot.py

* chore: update postprocessor SHA

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

Author: busunkim96

.github/.OwlBot.lock.yaml

@@ -13,5 +13,4 @@
 # limitations under the License.
 docker:
   image: gcr.io/cloud-devrel-public-resources/owlbot-python:latest
-  digest: sha256:8a5d3f6a2e43ed8293f34e06a2f56931d1e88a2694c3bb11b15df4eb256ad163
-# created: 2022-04-06T10:30:21.687684602Z
+  digest: sha256:266a3407f0bb34374f49b6556ee20ee819374587246dcc19405b502ec70113b6

.github/release-please.yml

@@ -1,2 +1,14 @@
 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: v2
+  handleGHRelease: true
+  releaseType: python
+- branch: v1
+  handleGHRelease: true
+  releaseType: python
+- branch: v0
+  handleGHRelease: true
+  releaseType: python

owlbot.py

@@ -160,6 +160,7 @@ def get_staging_dirs(
 # Update samples folder in CONTRIBUTING.rst
 s.replace("CONTRIBUTING.rst", "samples/snippets", "samples/samples")
 
+python.configure_previous_major_version_branches()
 # ----------------------------------------------------------------------------
 # Samples templates
 # ----------------------------------------------------------------------------