testsuite fails on Debian/Testing with python3.9

[Trophime]

Hi,
trying to package pytest-check 1.0.4 for Debian I run into these errors in the testsuite with python 3.9 on Debian/Testing:

=========================== short test summary info ============================
FAILED tests/test_check.py::test_watch_them_all_fail - AssertionError: assert...
FAILED tests/test_check.py::test_check_xfail - AssertionError: assert {'error...
FAILED tests/test_check.py::test_check_xfail_strict - AssertionError: assert ...
FAILED tests/test_check.py::test_check_and_assert - AssertionError: assert {'...
FAILED tests/test_check.py::test_stop_on_fail - AssertionError: assert {'erro...
FAILED tests/test_check_context_manager.py::test_context_manager_fail - Asser...
FAILED tests/test_check_context_manager.py::test_context_manager_fail_with_msg
FAILED tests/test_check_context_manager.py::test_stop_on_fail - AssertionErro...
FAILED tests/test_check_context_manager.py::test_stop_on_fail_with_msg - Asse...
FAILED tests/test_check_errors.py::test_setup_failure - AssertionError: asser...
FAILED tests/test_check_errors.py::test_teardown_failure - AssertionError: as...
FAILED tests/test_check_errors.py::test_mix - AssertionError: assert {'errors...
FAILED tests/test_check_func_decorator.py::test_fail - AssertionError: assert...
FAILED tests/test_maxfail.py::test_check_maxfail_1 - AssertionError: assert {...
FAILED tests/test_maxfail.py::test_check_maxfail_2 - AssertionError: assert {...
ERROR tests/test_check_fixture.py::test_check_fixture
==================== 15 failed, 24 passed, 1 error in 0.60s ====================
E: pybuild pybuild:367: test: plugin distutils failed with: exit code=1: cd /build/pytest-check-1.0.4/.pybuild/cpython3_3.9_pytest-check/build; python3.9 -m pytest tests
dh_auto_test: error: pybuild --test --test-pytest -i python{version} -p 3.9 returned exit code 13

Best

[okken]

PRs welcome