tests: fix Pytest RemovedInPytest4Warning

* Remove calls to get_marker() as it's deprecated, for context see:
  https://docs.pytest.org/en/latest/mark.html#marker-revamp-and-iteration

Change-Id: I465ff6a6e6bf1f83325e1e32f0d851feba702cb3

cumin/tests/integration/conftest.py

@@ -6,7 +6,7 @@
 def pytest_runtest_makereport(item, call):  # pylint: disable=unused-argument
     """If a custom variant_params marker is set, print a section with its content."""
     outcome = yield
-    marker = item.get_marker('variant_params')
+    marker = item.get_closest_marker('variant_params')
     if marker:
         rep = outcome.get_result()
         rep.sections.insert(0, ('test_variant parameters', marker.args))