PEP8 cleanup: fix whitespace before ':'

Reviewed-by: James Cameron <quozl@laptop.org>
Acked-by: Simon Schampijer <simon@laptop.org>
CC: Aleksey Lim <alsroot@member.fsf.org>

src/sugar/activity/activity.py

@@ -928,7 +928,7 @@ class _ClientHandler(dbus.service.Object, DBusProperties):
     def __get_filters_cb(self):
         logging.debug('__get_filters_cb')
         filters = {
-            CHANNEL + '.ChannelType'     : CHANNEL_TYPE_TEXT,
+            CHANNEL + '.ChannelType': CHANNEL_TYPE_TEXT,
             CHANNEL + '.TargetHandleType': CONNECTION_HANDLE_TYPE_CONTACT,
             }
         filter_dict = dbus.Dictionary(filters, signature='sv')