removed pytestmark in test_partial_slicing

Author: raghavendranath

pandas/tests/indexes/datetimes/test_partial_slicing.py

@@ -19,12 +19,12 @@
 )
 import pandas._testing as tm
 
-pytestmark = pytest.mark.filterwarnings(
-    "ignore:Parsing non-ISO datetime strings:pandas.errors.Pandas4Warning"
-)
-
 
 class TestSlicing:
+    pytestmark = pytest.mark.filterwarnings(
+        "ignore:Parsing non-ISO datetime strings:pandas.errors.Pandas4Warning"
+    )
+
     def test_string_index_series_name_converted(self):
         # GH#1644
         df = DataFrame(