Pin pytest<5 as it breaks pytest-flake8, see:

krassowski · krassowski · commit 41e01e82c1e7 · 2022-11-19T11:43:30.000Z
tholo/pytest-flake8#87
diff --git a/requirements-dev.txt b/requirements-dev.txt
@@ -1,4 +1,4 @@
-pytest
+pytest<5
 pytest-cov
 pytest-flake8
 mypy
