Netpbmfile

- Improve type hints.
- Drop support for Python 3.9, support Python 3.13.

- Fix docstring examples not correctly rendered on GitHub.

- Support NumPy 2.

- Fix linting issues.
- Add py.typed marker.

- Drop support for Python 3.8 and numpy < 1.21 (NEP29).
- Improve type hints.

- Several breaking changes:
- Rename magicnum to magicnumber (breaking).
- Rename tupltypes to tupltype (breaking).
- Change magicnumber and header properties to str (breaking).
- Replace pam parameter with magicnumber (breaking).
- Move byteorder parameter from NetpbmFile.asarray to NetpbmFile (breaking).
- Fix shape and axes properties for multi-image files.
- Add maxval and tupltype parameters to NetpbmFile.fromdata and imwrite.
- Add option to write comment to PNM and PAM files.
- Support writing PGX and text formats.
- Add Google style docstrings.
- Add unittests.