Apply ruff/flake8-pytest-style rule PT031 (#3269)

PT031 `pytest.warns()` block should contain a single simple statement

Co-authored-by: Davis Bennett <davis.v.bennett@gmail.com>

Author: DimitriPapadopoulos

pyproject.toml

@@ -325,7 +325,6 @@ ignore = [
     "ANN401",
     "PT011",  # TODO: apply this rule
     "PT030",  # TODO: apply this rule
-    "PT031",  # TODO: apply this rule
     "RET505",
     "RET506",
     "RUF005",

tests/test_api.py

@@ -470,7 +470,7 @@ def test_tree() -> None:
     g3.create_group("baz")
     g5 = g3.create_group("qux")
     g5.create_array("baz", shape=(100,), chunks=(10,), dtype="float64")
-    with pytest.warns(DeprecationWarning):
+    with pytest.warns(DeprecationWarning):  # noqa: PT031
         assert repr(zarr.tree(g1)) == repr(g1.tree())
         assert str(zarr.tree(g1)) == str(g1.tree())