work around typing issue in psycopg 3.3

Author: lonvia

src/nominatim_db/config.py

@@ -7,7 +7,7 @@
 """
 Nominatim configuration accessor.
 """
-from typing import Union, Dict, Any, List, Mapping, Optional
+from typing import Union, Dict, Any, List, Mapping, Optional, cast
 import importlib.util
 import logging
 import os
@@ -197,7 +197,7 @@ def get_database_params(self) -> Mapping[str, Union[str, int, None]]:
         if dsn.startswith('pgsql:'):
             return dict((p.split('=', 1) for p in dsn[6:].split(';')))
 
-        return conninfo_to_dict(dsn)
+        return cast(Mapping[str, Union[str, int, None]], conninfo_to_dict(dsn))
 
     def get_import_style_file(self) -> Path:
         """ Return the import style file as a path object. Translates the