Use int64 instead of Int64 for dtype

Author: Bruno P. Kinoshita

pandas/tests/io/formats/test_to_csv.py

@@ -556,7 +556,7 @@ def test_to_csv_zip_arguments(self, compression, archive_name):
             archived_file = os.path.basename(zp.filelist[0].filename)
             assert archived_file == expected_arcname
 
-    @pytest.mark.parametrize("df_new_type", ["Int64"])
+    @pytest.mark.parametrize("df_new_type", ["int64"])
     def test_to_csv_na_rep_long_string(self, df_new_type):
         # see gh-25099
         df = pd.DataFrame([np.nan] * 3, columns=['c'], dtype=df_new_type)