Add python-qtpy into appimage recipe to build with Qt4

Author: g1itch

packages/AppImage/PyBitmessage.yml

@@ -11,6 +11,7 @@ ingredients:
     - python-msgpack
     - python-qrcode
     - python-qt4
+    - python-qtpy
     - python-setuptools
     - python-sip
     - python-six