[3.9] gh-139400: Make sure that parent parsers outlive their subparsers in `pyexpat` (GH-139403)#139614

ambv merged 3 commits intopython:3.9python/cpython:3.9from

hartwork:backport-6edb2dd-3.9hartwork/cpython:backport-6edb2dd-3.9Copy head branch name to clipboard