bump to python 39

[kod-kristoff]

• ci: add uv based workflows
• ci: use env namespace
• chore: add uv based Makefile
• ci: remove unused actions
• ci(test): fix python-version
• ci: bump uv to 0.4.18
• ci: do not use hashes from workflow file
• ci: set python 3.9 as minimum version
• ci: also test for python 3.13
• ci: also test for python 3.14-dev
• ci(deps): bump uv to 0.5.1
• ci: use setup-uv action
• ci: bump codecov-action to v5
• chore: update uv export
• chore: fix typo
• chore: fix uv export
• chore: do not emit project
• ci: only cache uv, not .venv
• ci: add --all-packages to uv sync calls
• chore: add --all-packages to uv sync calls
• ci: bump codecov-action to v5
• ci: use make install-dev where possible
• chore: use uv instead of pdm
• chore: migrate pre-commit-config
• chore: remove old Makefiles and CI
• chore: adapt Makefile to project
• ci: rename release workflow
• ci: configure CI for project
• feat: bump python-version to 3.9
• chore: config git-cliff to use Keep-a-changelog format