Type hints: Add PYI (flake8-pyi) to Ruff and fix errors

[hugovk]

Add PYI to Ruff to run the flake8-pyi linting rules related to type hints and fix the errors:

Tests/test_file_libtiff.py:246:14: PYI024 Use `typing.NamedTuple` instead of `collections.namedtuple`
Tests/test_lib_pack.py:18:18: PYI041 Use `float` instead of `int | float`
Tests/test_lib_pack.py:242:18: PYI041 Use `float` instead of `int | float`
src/PIL/PdfParser.py:85:5: PYI024 Use `typing.NamedTuple` instead of `collections.namedtuple`
src/PIL/TarIO.py:61:9: PYI034 `__enter__` methods in classes like `TarIO` usually return `self` at runtime
src/PIL/TiffTags.py:24:15: PYI024 Use `typing.NamedTuple` instead of `collections.namedtuple`
src/PIL/_imaging.pyi:1:1: PYI044 `from __future__ import annotations` has no effect in stub files, since type checkers automatically treat stubs as having those semantics
src/PIL/_imagingcms.pyi:1:1: PYI044 `from __future__ import annotations` has no effect in stub files, since type checkers automatically treat stubs as having those semantics
src/PIL/_imagingft.pyi:1:1: PYI044 `from __future__ import annotations` has no effect in stub files, since type checkers automatically treat stubs as having those semantics
src/PIL/_imagingmath.pyi:1:1: PYI044 `from __future__ import annotations` has no effect in stub files, since type checkers automatically treat stubs as having those semantics
src/PIL/_imagingmorph.pyi:1:1: PYI044 `from __future__ import annotations` has no effect in stub files, since type checkers automatically treat stubs as having those semantics
src/PIL/_webp.pyi:1:1: PYI044 `from __future__ import annotations` has no effect in stub files, since type checkers automatically treat stubs as having those semantics
Found 12 errors.

I skipped PYI034. The fix is to return typing.Self, but that was only added in 3.10, or typing_extensions.Self from the backport, which we're not using. Open to other solutions.

• https://docs.astral.sh/ruff/rules/#flake8-pyi-pyi
• https://github.com/PyCQA/flake8-pyi
• https://docs.python.org/3/library/typing.html#typing.Self