fix styling error caught by github actions

Author: Neal Muppidi

pandas/tests/indexing/test_at.py

@@ -10,11 +10,11 @@
     CategoricalDtype,
     CategoricalIndex,
     DataFrame,
+    DatetimeIndex,
     MultiIndex,
     Series,
     Timestamp,
     to_datetime,
-    DatetimeIndex,
 )
 import pandas._testing as tm
 
@@ -99,17 +99,17 @@ def test_at_setitem_categorical_missing(self):
 
         tm.assert_frame_equal(df, expected)
 
-    @pytest.mark.parametrize("row", (to_datetime('2019-01-01'), '2019-01-01'))
+    @pytest.mark.parametrize("row", (to_datetime("2019-01-01"), "2019-01-01"))
     def test_at_datetime_index(self, row):
         df = DataFrame(
             data=[[1] * 2] * 2,
-            columns=['one', 'two'],
+            columns=["one", "two"],
             index=DatetimeIndex(data=["2019-01-01", "2019-01-02"]),
         )
 
-        df.at[row, 'one'] = 0.5
-        assert df.at[row, 'one'] == 0.5
-        assert df['one'].dtype == 'float64'
+        df.at[row, "one"] = 0.5
+        assert df.at[row, "one"] == 0.5
+        assert df["one"].dtype == "float64"
 
     def test_at_setitem_multiindex(self):
         df = DataFrame(