Change in maintainer address

[Callum McKenzie <callum spooky-possum org>]

Just a quick note to say that the maintainer email address for
gnome-games has changed to:

callum spooky-possum org

The maintainer hasn't changed, just the address. 

The reason for the change is the same reason I've been bad at responding
to bug reports recently: changing jobs and changing city. Service should
improve soonish.

 - Callum