typeguard requires pytest<7

setup.py

@@ -49,7 +49,8 @@ WEB_FILES = ["web/internal_data/css/icon.png",
 install_requires = ["defusedxml", "passlib", "vobject>=0.9.6",
                     "python-dateutil>=2.7.3",
                     "setuptools; python_version<'3.9'"]
-tests_require = ["pytest", "pytest-cov", "pytest-flake8", "pytest-isort",
+# typeguard requires pytest<7
+tests_require = ["pytest<7", "pytest-cov", "pytest-flake8", "pytest-isort",
                  "typeguard", "waitress",
                  "pytest-mypy; implementation_name=='cpython'",
                  "types-setuptools; implementation_name=='cpython'"]