Cherry-pick fix for check failure, Use PEP 517 workflow, Stop hardcoding Python version, Use SPDX license

• Cherry-pick fix for check failure
  • Fix two tests which are failing because there are no package groups in the core repo and base-devel is a meta package instead of a package group now.
  • archlinux/pyalpm@820493a9
• Change to a PEP 517 based workflow
  • checkdepends tested as being used in only in check with pkgctl build --nocheck
• Stop hardcoding the Python version
• Change to SPDX license identifier
  • https://gitlab.archlinux.org/archlinux/pyalpm/-/blob/0.10.6/setup.cfg?#L10

I believe this completes the remove-hardcoded-python-version todo list.