re-fix case_when test

Author: jbrockmendel

pandas/tests/series/methods/test_case_when.py

@@ -2,7 +2,6 @@
 import pytest
 
 from pandas import (
-    NA,
     DataFrame,
     Series,
     array as pd_array,
@@ -100,7 +99,7 @@ def test_case_when_multiple_conditions_replacement_extension_dtype(df):
             (df["a"].gt(1) & df["b"].eq(5), pd_array([1, 2, 3], dtype="Int64")),
         ],
     )
-    expected = Series([1, 2, NA], dtype="Float64")
+    expected = Series([1, 2, np.nan], dtype="Float64")
     tm.assert_series_equal(result, expected)