CLSA-2026-1778535928 python: Fix of 2 CVEs

CVE-2021-3733: fix ReDoS in urllib2 AbstractBasicAuthHandler regex; the legacy '?:.,' prefix is replaced with the upstream-3.x form '?:^|,' and the scheme charset excludes ',' to prevent quadratic backtracking on crafted WWW-Authenticate headers - CVE-2021-23336: stop accepting ';' as a default...