Removed unnecessary change in test_string

Author: eicchen

pandas/tests/arrays/string_/test_string.py

@@ -258,7 +258,8 @@ def test_astype_float(dtype, any_float_dtype):
     # Don't compare arrays (37974)
     ser = pd.Series(["1.1", pd.NA, "3.3"], dtype=dtype)
     result = ser.astype(any_float_dtype)
-    expected = pd.Series([1.1, np.nan, 3.3], dtype=any_float_dtype)
+    item = np.nan if isinstance(result.dtype, np.dtype) else pd.NA
+    expected = pd.Series([1.1, item, 3.3], dtype=any_float_dtype)
     tm.assert_series_equal(result, expected)