feat: added python-version-strategy config option, to enable enforcing use of the lowest supported (approximate) version

[ErikBjare]

Description:

Adds a python-version-strategy config option that enables overriding the version-picking strategy provided by the Python version specifier from >= and ^ to ~.

This is very useful when the version specified in python-version-file is a version constraint such as ^3.8 but where you usually want to test against the lowest supported version (with the highest patch version).

Related issue:

Filed a feature request for this here: #774

Check list:

• [ ] Mark if documentation changes are required.
  • Not done, yet (will do if PR is likely to be accepted)
• [ ] Mark if tests were added or updated to cover the changes.
  • Not done, yet (will do if PR is likely to be accepted)

PRs I will merge if this change is accepted:

• https://github.com/ActivityWatch/aw-core/pull/124
• https://github.com/ActivityWatch/aw-client/pull/80
• https://github.com/ActivityWatch/aw-qt/pull/101
• https://github.com/ActivityWatch/aw-server/pull/148
• https://github.com/ActivityWatch/aw-watcher-afk/pull/65
• https://github.com/ActivityWatch/aw-watcher-window/pull/93
• https://github.com/ActivityWatch/aw-watcher-input/pull/29