MT#22619 Switch Debian Source to Sipwise GitHub mirror

Git daemon which provided Sipwise anonymous access to
internal Git repository is deprecated. Also it is
useless to point public GitHub repository to the internal git server.

Change-Id: Ib96777255b69bebf590fadf1cab9aadaa58400b5

debian/copyright

@@ -1,6 +1,6 @@
 Format: http://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
 Upstream-Name: repoapi
-Source: git://git.mgm.sipwise.com/repoapi
+Source: https://github.com/sipwise/repoapi.git
 
 Files: *
 Copyright: 2015 Sipwise GmbH, Austria