Update Homepage URL to github.io

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

debian/control

@@ -4,7 +4,7 @@ Priority: optional
 Maintainer: Brandon Holtsclaw <me@brandonholtsclaw.com>
 Uploaders: Jeremy T. Bouse <jbouse@debian.org>,
            Benjamin Drung <bdrung@debian.org>
-Homepage: http://apt-mirror.github.com/
+Homepage: https://apt-mirror.github.io/
 Build-Depends: debhelper (>= 9), lsb-release
 Standards-Version: 3.9.8
 Vcs-Browser: https://salsa.debian.org/debian/apt-mirror