QuaLiKiz-pythontools CI, package creation and upload

This MR makes major changes to the QuaLiKiz-pythontools CI, namely:

• Removes the broken and hacky Heimdall-like install job (6e3f683b)
• Bring CI in line with other "Karel Pythontools" (39983795)
• Additionally run the documentation generation on branches named (39983795, fd3ec654)
  • karel/*
  • feature/*
  • bugfix/*
  • hotfix/*
• Use pip/python cache and venv as in gitlab.com examples. (8f106c8e, c1414148)
• Use bash env variables for pip and python (beb4c5b5)
• install_docker_heimdall_like -> install_docker_heimdall_like_user_install and install like it is on Heimdall (0ff745ef, fd833700)
• Test the non-editable install in install_docker_heimdall_like_user_install_noneditable
• Build manylinux Python packages (e07e5c9d, 29d20d70)
• Use default stages build, run, test, and deploy; Removed doc stage. (d9a35126)
• Remove logic from setup.py and move it to pyproject.toml and setup.cfg (c90cf5a9, fe2cc0ba)
• Deploy packages to test.pypi (for now) (cb6f040f, 1df9354d, 649bb955, 1c13b256)