add missing gnupg dependency

i can't believe i missed this

debian/control

@@ -9,7 +9,7 @@ Vcs-Git: git://git.monkeysphere.info/monkeysign
 
 Package: monkeysign
 Architecture: all
-Depends: ${shlibs:Depends}, ${misc:Depends}, ${python:Depends}
+Depends: ${shlibs:Depends}, ${misc:Depends}, ${python:Depends}, gnupg
 Recommends: python-qrencode, python-gtk2, python-zbar, python-zbarpygtk
 Description: OpenPGP key signing and exchange for humans
  monkeysign is a tool to overhaul the OpenPGP keysigning experience