Replace regular expression grep of desktop file with the Gio API for this.

lutris/services/xdg.py

@@ -166,12 +166,11 @@ class XDGGame(ServiceGame):
     @staticmethod
     def get_desktop_entry_path(xdg_app):
         """Retrieve the Path variable from the .desktop file"""
-        desktop_entry = xdg_app.get_filename()
-        with open(desktop_entry, 'r') as f:
-            contents = f.read()
-            match = re.search(r'^Path=(.*)$', contents, re.MULTILINE)
-            if match:
-                return match.group(1)
+
+        # I expect we'll only see DesktopAppInfos here, but just in case
+        # we get something else, we'll make sure.
+        if hasattr(xdg_app, "get_string"):
+            return xdg_app.get_string("Path")
         return None
 
     @staticmethod