fix: reject invalid interpreter tags

[deepakganesh78]

Fixes #577.

Summary

• validate every compressed interpreter-tag member as an identifier before constructing Tag objects
• reject malformed wheel names such as playlyfe-0.1.1-2.7.6-none-any.whl, which previously expanded into the numeric interpreter tags 2, 7, and 6
• preserve support for custom implementation identifiers and wrap parser failures as InvalidWheelFilename
• update the API documentation and changelog

Compatibility

The validation uses str.isidentifier() rather than a fixed implementation allowlist. Existing well-known tags, custom implementation identifiers, uppercase input normalized by Tag, and every tag produced by sys_tags() continue to parse. Non-empty ABI and platform components retain their existing behavior.

Tests

• python -m pytest tests/test_tags.py::TestParseTag tests/test_utils.py -q — 105 passed
• python -m pytest -q — 62,399 passed, 1 skipped, 427 deselected
• targeted ruff-check, ruff-format, and reStructuredText pre-commit hooks — passed
• python -m nox -s docs — HTML, LaTeX, and doctest builds passed; 418 doctests passed
• compatibility probe over all 45 local sys_tags() entries plus custom interpreter identifiers — passed
• validation-boundary probe confirming non-empty ABI/platform components remain accepted — passed

nox -s lint also passed all hooks except the repository's pinned mypy hook on Windows: mypy 2.1 rejects the configured Python 3.9 target and reports the existing os.confstr platform error in _manylinux.py.

[henryiii]

The PEP said it was an identifier, so I think this is a valid restriction, and will protect against some mistakes.

[henryiii]

Thanks!