Treat `pytest` warnings as errors #454

Job	Run time
Build distribution packages	21s
Cross-arch tests with nox (arm64, ubuntu-20.04, 3.11, pytest_min)	4m 25s
Test documentation website generation	0s
Cross-arch tests with nox (arm64, ubuntu-20.04, 3.11, pytest_max)	4m 18s
Test with nox (ubuntu-20.04, 3.11, ci_checks_max)	35s
Test with nox (ubuntu-20.04, 3.11, pytest_min)	5m 55s
Test package installation in different architectures	1m 32s
Cross-arch tests with nox	1s
Test with nox	1s
Publish documentation website to GitHub pages	0s
Create GitHub release	0s
Publish packages to PyPI	0s
	17m 8s

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