iptables: bump std-versions to 4.1.3

Bump compliance with standards.
Signed-off-by: Arturo Borrero Gonzalez <arturo@debian.org>

debian/control

@@ -14,7 +14,7 @@ Build-Depends: autoconf,
                libnfnetlink-dev,
                libnftnl-dev,
                libtool (>= 2.2.6)
-Standards-Version: 4.0.0
+Standards-Version: 4.1.3
 Homepage: http://www.netfilter.org/
 Vcs-Git: https://salsa.debian.org/pkg-netfilter-team/pkg-iptables
 Vcs-Browser: https://salsa.debian.org/pkg-netfilter-team/pkg-iptables
@@ -45,7 +45,7 @@ Depends: libip4tc-dev (>= ${source:Version}),
          ${misc:Depends}
 Architecture: any
 Multi-Arch: same
-Priority: extra
+Priority: optional
 Section: oldlibs
 Description: transitional dummy package
  This is a transitional dummy package. It can safely be removed.