packaging 26.3

[amotl]

packaging 26.3 was released on August 4, 2026. It seems to include interesting changes in the area of packaging.version, so verlib2 should consider backporting them.

• Add a public VersionRange API and SpecifierSet.to_range(), representing the versions a specifier set accepts as an interval set that supports intersection, union, difference, complement, set relations, membership tests, and filtering. VersionRange.to_specifier_set() converts a range back to a SpecifierSet where a PEP 440 form exists. (feat: add public PEP 440 compliance VersionRange class pypa/packaging#1267, Add VersionRange.to_specifier_set pypa/packaging#1270, Add set relations and difference to VersionRange pypa/packaging#1298)

• Raise InvalidVersion instead of TypeError when Version is given a non-string. (fix(version): reject non-string versions consistently pypa/packaging#1319)

• Raise InvalidVersion for non-string pre-release letters passed to Version.from_parts. (fix(version): raise InvalidVersion for non-str pre letters in from_parts pypa/packaging#1241)

• Fix an AttributeError when hashing internally trimmed versions. (fix(version): set _hash_cache when copying a Version in _TrimmedRelease pypa/packaging#1242)

• Fix SpecifierSet.is_unsatisfiable for post-release boundary intersections. (fix: post-release boundary intersections and unsatisfiable cases pypa/packaging#1257)