chore: Add script to automate PR merging

[jinseopkim0]

This script automates the process of retrying and merging pull requests by checking the status of Kokoro tests.

Prerequisites:

• Go must be installed (https://golang.org/doc/install).
• A GitHub personal access token with repo scope must be set in the GITHUB_TOKEN environment variable.

Example Usage:

export GITHUB_TOKEN="<your GitHub token>"
cd .github/scripts
go run ./release_manager_merge_bot.go <PR URL>

[blakeli0]

Thanks for moving the scripts to google-cloud-java, Jin Seop! I think we usually put Github related scripts to .github folder. Maybe another subfolder like PR_merging_automation?

[meltsufin]

Why isn't "Enable- auto-merge" sufficient?

[jinseopkim0]

Thanks for moving the scripts to google-cloud-java, Jin Seop! I think we usually put Github related scripts to .github folder. Maybe another subfolder like PR_merging_automation?

Thanks for the feedback. I put the script in .github/scripts. Please let me know if you disagree with this decision.

[jinseopkim0]

Why isn't "Enable- auto-merge" sufficient?

Thanks for the question. This script is a temporary solution to ease the work of release managers that have to continually retry flaky kokoro tests. The script retries kokoro tests if they fail, and auto-merge does not retry kokoro tests. We have a long term solution to track the flaky tests and fix them or disable them.