Apply ruff/Perflint rule (#1136)

PERF401 Use a list comprehension to create a transformed list

A comprehension is a more efficient way to initialise a list than
successive append() calls.

twine/repository.py

@@ -96,8 +96,7 @@ def _convert_data_to_list_of_tuples(data: Dict[str, Any]) -> List[Tuple[str, Any
             if key in KEYWORDS_TO_NOT_FLATTEN or not isinstance(value, (list, tuple)):
                 data_to_send.append((key, value))
             else:
-                for item in value:
-                    data_to_send.append((key, item))
+                data_to_send.extend((key, item) for item in value)
         return data_to_send
 
     def set_certificate_authority(self, cacert: Optional[str]) -> None: