[CI] Python 3.7 not available in ubuntu-latest

[zeritti]

Describe the bug a clear and concise description of what the bug is.

Step actions/setup-python@5 in workflow job lint-test set with python-version=3.7 fails as this version is not available in the current image ubuntu-latest. It appears that the image has already been updated to 24.04 which does not include python 3.7 any longer:

  Error: The version '3.7' with architecture 'x64' was not found for Ubuntu 24.04.
  The list of all available versions can be found here:
  https://raw.githubusercontent.com/actions/python-versions/main/versions-manifest.json

Steps with that action fail, e.g. https://github.com/prometheus-community/helm-charts/actions/runs/12444946805/job/34745736173?pr=5053

On image update to Ubuntu 24.04: Ubuntu-latest workflows will use Ubuntu-24.04 image

The affected workflow jobs may need an adjustment.

[dotdc]

PR to fix: #5085