[3.12] gh-136063: fix quadratic-complexity parsing in `email.message._parseparam` (GH-136072) (#140829)

gh-136063: fix quadratic-complexity parsing in `email.message._parseparam` (GH-136072)
(cherry picked from commit 680a5d070f59798bb88a1bb6eb027482b8d85c34)

Co-authored-by: Bénédikt Tran <[email protected]>
3 files changed