fix: set output_dir default value

Author: saibatizoku

utilities/ideascale-importer/ideascale_importer/ideascale/importer.py

@@ -232,7 +232,7 @@ def __init__(
         event_id: int,
         proposals_scores_csv_path: Optional[str],
         ideascale_api_url: str,
-        output_dir: Optional[Path],
+        output_dir: Optional[Path] = None,
     ):
         """Initialize the importer."""
         self.api_token = api_token