Fix import file dialog in db editor filter set as sqlite automatically

Now when the import dialog is opened
from the db editor, the file type
filter is automatically set to show
all filetypes instead of just .sqlite
files.

Re #2168

spinetoolbox/spine_db_editor/widgets/spine_db_editor.py

@@ -470,7 +470,7 @@ def import_file(self, checked=False):
             self,
             "Import file",
             self._get_base_dir(),
-            "SQLite (*.sqlite);; JSON file (*.json);; Excel file (*.xlsx)",
+            "All files (*);;  SQLite (*.sqlite);; JSON file (*.json);; Excel file (*.xlsx)",
         )
         self.qsettings.endGroup()
         if not file_path:  # File selection cancelled