Add comment for the try packaging finally clause

Author: gounux

libqfieldsync/offline_converter.py

@@ -676,6 +676,8 @@ def _export_basemap_as_mbtiles(
         # connect subtask feedback progress signal
         self._feedback.progressChanged.connect(self._on_tiles_gen_alg_progress_changed)
 
+        # we use a try clause to make sure the feedback's `progressChanged` signal
+        # is disconnected in the finally clause.
         try:
             results, ok = alg.run(params, context, self._feedback)