Currently the check for the security archive in Debian/Ubuntu fails, if
the archive is not hosted on security.{debian,ubuntu}.org and the URL
does have trailing slash, such as this:
deb http://deb.debian.org/debian-security/ stretch/updates main
Change the regular expression to allow for a trailing slash in the URL
when filtering the package sources lists.
Signed-off-by: Timo Sigurdsson <public_timo.s@silentcreek.de>