CLSA-2026-1777548617 Fix CVE(s): CVE-2026-4519, CVE-2026-4786

SECURITY UPDATE: webbrowser.open accepts URLs with leading dashes - debian/patches/CVE-2026-4519-CVE-2026-4786.patch: reject URLs whose lstrip starts with '-' in Lib/webbrowser.py; also fix bypass via %action substitution in UnixBrowser.open. - CVE-2026-4519 - CVE-2026-4786...