python: Reformat some files to keep style-check-diff happy

The version of `black` on the CI server wanted these changes. Make them
to keep the `style-check-diff` CI job from constantly failing.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

gobject/tests/mkenums.py

@@ -225,7 +225,7 @@ file-tail
 
             # Known substitutions for generated filenames.
             result.subs.update(
-                {"filename": h_file.name, "basename": os.path.basename(h_file.name),}
+                {"filename": h_file.name, "basename": os.path.basename(h_file.name)}
             )
 
             return result