CI: Linux py36_locale failures with pytest DeprecationWarning

[simonjayhawkins]

tests using async_mark are failing cc @alimcmaster1

=========================== short test summary info ============================
ERROR pandas/tests/arrays/categorical/test_warnings.py::TestCategoricalWarnings
ERROR pandas/tests/arrays/categorical/test_warnings.py::TestCategoricalWarnings
ERROR pandas/tests/frame/test_api.py::TestDataFrameMisc - pytest.PytestDeprec...
ERROR pandas/tests/frame/test_api.py::TestDataFrameMisc - pytest.PytestDeprec...
ERROR pandas/tests/indexes/test_base.py::TestIndex - pytest.PytestDeprecation...
ERROR pandas/tests/indexes/test_base.py::TestIndex - pytest.PytestDeprecation...
ERROR pandas/tests/resample/test_resampler_grouper.py - pytest.PytestDeprecat...
ERROR pandas/tests/resample/test_resampler_grouper.py - pytest.PytestDeprecat...
ERROR pandas/tests/series/test_api.py::TestSeriesMisc - pytest.PytestDeprecat...
ERROR pandas/tests/series/test_api.py::TestSeriesMisc - pytest.PytestDeprecat...
= 71242 passed, 1936 skipped, 1024 xfailed, 156 warnings, 10 errors in 655.85s (0:10:55) =

[simonjayhawkins]

failing

pytest                    6.0.1                    py36_0  
pytest-asyncio            0.10.0                py36_1000  
pytest-azurepipelines     0.8.0                      py_0  
pytest-forked             1.2.0                      py_0  
pytest-xdist              1.33.0                     py_0 

passing

pytest                    5.4.3                    py36_0  
pytest-asyncio            0.10.0                py36_1000  
pytest-azurepipelines     0.8.0                      py_0  
pytest-forked             1.2.0                      py_0  
pytest-xdist              1.33.0                     py_0