Bump Standards-Version to 4.6.1

Signed-off-by: Benjamin Drung <benjamin.drung@canonical.com>

debian/control

@@ -6,7 +6,7 @@ Uploaders: Jeremy T. Bouse <jbouse@debian.org>,
            Benjamin Drung <bdrung@debian.org>
 Homepage: https://apt-mirror.github.io/
 Build-Depends: debhelper-compat (= 13), lsb-release
-Standards-Version: 3.9.8
+Standards-Version: 4.6.1
 Vcs-Browser: https://salsa.debian.org/debian/apt-mirror
 Vcs-Git: https://salsa.debian.org/debian/apt-mirror.git