fix expected columns dtype

pandas/tests/io/test_feather.py

@@ -215,6 +215,10 @@ def test_read_feather_dtype_backend(
  }
  )
 
+ if using_infer_string:
+ expected.columns = expected.columns.astype(
+ pd.StringDtype(string_storage, na_value=np.nan)
+ )
  tm.assert_frame_equal(result, expected)
 
  def test_int_columns_and_index(self):