GeezerVison

Manual backport of #154867 to the security branch, cherry-picked from the 3.13 backport (commit b30c7fa).

The only conflict was in Lib/csv.py: 3.12 does not have gh-103925, so its patterns end with (?:$|\n) where the 3.13 pre-image had (?:$|\r|\n). After the resolution _guess_quote_and_delimiter() is identical to the 3.13 one.

Sniffing '"abcdefghijklmnopqrstuvwxyz"\n' * n with delimiters=',:|\t' takes 0.248, 0.977, 3.891 and 15.316 s for n = 1250, 2500, 5000 and 10000 before the change, and 0.026, 0.055, 0.109 and 0.216 s after it.

• Issue: csv.Sniffer().sniff() Hangs on Single-Column Data #98820