Backport Fedora spec file changes
During the review of the spec file for its inclusion in Fedora [1], a few changes were performed:
- Changed the license to a valid SPDX expression
- Added a missing dependency to systemd-rpm-macros
- Renamed the Python package to use a python3- prefix
- Removed the dependency to Python 3 [2]
[1] https://bugzilla.redhat.com/show_bug.cgi?id=2257727
[2] https://docs.fedoraproject.org/en-US/packaging-guidelines/Python/#_dependencies