suppress typing error

Author: jorisvandenbossche

pandas/core/arrays/string_.py

@@ -301,7 +301,7 @@ def _get_common_dtype(self, dtypes: list[DtypeObj]) -> DtypeObj | None:
             # if both python and pyarrow storage -> priority to pyarrow
             storage = "pyarrow"
         else:
-            storage = next(iter(storages))
+            storage = next(iter(storages))  # type: ignore[assignment]
 
         na_value: libmissing.NAType | float
         if len(na_values) == 2: