xfsprogs: swap src url to HTTPS

This swaps the fetchgit call to be more consistent with the majority of other
NixPkgs fetchgit calls. Moreover, almost every network will be able to do HTTPS,
while some enterprise networks may limit external SSH access.

pkgs/tools/filesystems/xfsprogs/default.nix

···
   version = "4.14.0";
 
   src = fetchgit {
-    url = "git://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git";
-    rev = "refs/tags/v${version}";
+    url = "https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git";
+    rev = "v${version}";
     sha256 = "19mg3avm188xz215hqbbh7251q27qwm7g1xr8ffrjwvzmdq55rxj";
   };