fix: files/support-type JSON serialization error (#26842)

api/controllers/console/files.py

@@ -108,4 +108,4 @@ class FileSupportTypeApi(Resource):
     @login_required
     @account_initialization_required
     def get(self):
-        return {"allowed_extensions": DOCUMENT_EXTENSIONS}
+        return {"allowed_extensions": list(DOCUMENT_EXTENSIONS)}