Simplify release and start steps further

[andy-maier]

The end goal for releasing a version is:

• user performs some upfront checks:
  • no uncommitted changes in local repo
  • no open issues&PRs on the milestone for the version to be released
  • no safety issues
  • no dependabot issues
• user runs "make release_pr" to perform all actions up to the creating release PR
• merging the release PR triggers all remaining actions

The end goal for starting a new version is:

• user performs some upfront checks:
  • no uncommitted changes in local repo
• user runs "make start_pr" to perform all actions up to creating the start PR
• merging the start PR triggers all remaining actions

[andy-maier]

Started working on this, and added a new (still undocumented) make target "release_pr". Current status is that it successfully creates the release PR, but the following test workflow is not triggered. See PR #1639

[andy-maier]

I have created issue https://github.com/actions/github-script/issues/484 to discuss why the test workflow is not triggered.

[andy-maier]

After several attempts, I have given up on automating the release PR creation.

The basic sets of attempts were:

• Using the standard GITHUB_TOKEN in the GITHUB_TOKEN variable -> Creates the PR, but does not trigger the test workflow. This is caused by the restriction stated here: https://docs.github.com/actions/security-for-github-actions/security-guides/automatic-token-authentication#using-the-github_token-in-a-workflow

• Using a Personal Access Token and passing it in the GITHUB_TOKEN variable (PR #1645) -> Creates the PR, but does not trigger the test workflow.

• Using a Personal Access Token and passing it in the github-token parameter (PR #1653) -> Cannot create the PR and fails at the GitHub REST API with HTTP status 403 "Resource not accessible by personal access token".

• Using a dummy GitHub App to generate a GitHub App Token using actions/create-github-app-token, and passing the token in the github-token parameter (PR #1655) -> Cannot create the PR and fails at the GitHub REST API with HTTP status 403 "Resource not accessible by personal access token".

Additional artifacts for for the attempts with the personal access token:

• A Personal Access Token "zhmcclient_create_pr" in https://github.com/settings/tokens?type=beta
• An org level secret "PAT_ZHMCCLIENT_CREATE_PR" with the value of the Personal Access Token

Additional artifacts for for the attempts with the dummy GitHub App:

• A definition of a GitHub App "zhmcclient dummy app" n https://github.com/organizations/zhmcclient/settings/apps
• An installation of that App in the zhmcclient org
• Org level secrets APP_ID and APP_PRIVATE_KEY with ID and private key of the installed App

[andy-maier]

PR #1656 removed all of the code for support fo release_pr.

It can be re-established by reverting the commit in that PR.