Add ptest and upgrade to release 0.13.1:
- pyproject.toml: add pytest as dev dependency
- Import Self from type_checking if needed to be compat with 3.9
- CI: run pytest via uv
- CI: test against multiple python versions
Signed-off-by: Leon Anavi <leon.anavi@konsulko.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
