Bugfix release:
- Fix breaking issues on Windows builds (on newer AppVeyor and GHA runners)
- Use colorized compiler output where available
- Update OS and compiler versions for GitHub Actions (drop Ubuntu 18)
- Minor improvements, updates and bug fixes.
Because of changes in the Python unittest
module, the unit test of ci-scripts requires Python >= 3.2.
The ci-scripts module itself requires Python >= 2.7.