version dependency on openssh-client

This is only to ensure that it's as new a version as it was built with, so
partial upgrades work.

debian/control

@@ -37,7 +37,7 @@ Depends: ${misc:Depends}, ${shlibs:Depends},
 	uuid,
 	rsync,
 	wget | curl,
-	openssh-client
+	openssh-client (>= 1:5.6p1)
 Suggests: graphviz, bup, gnupg
 Description: manage files with git, without checking their contents into git
  git-annex allows managing files with git, without checking the file