[3.10] gh-94996: Disallow parsing pos only params with feature_version < (3, 8) (GH-95935)

(cherry picked from commit https://github.com/python/cpython/commit/b5e3ea286289fcad12be78480daf3756e350f69f)

Co-authored-by: Shantanu <12621235+hauntsaninja@users.noreply.github.com>

Automerge-Triggered-By: GH:lysnikolaou