[3.13] gh-86155: Fix data loss after unclosed script or style tag in HTMLParser (GH-22658) (GH-133845)

When calling .close() the HTMLParser should flush all remaining content,
even when that content is in an unclosed script or style tag.
(cherry picked from commit 53383e90e4df7029f792b7aa81aa2e4cff348ed0)

Co-authored-by: Waylan Limberg <waylan.limberg@icloud.com>