pkg_resources not found

`setuptools` has removed `pkg_resources` from its package, which causes a failure in our test environment because `pytest-rerunfailures` imports it. It is not defined as a dependency in the `pyproject.toml`. Should it be, or should this project also try to work, e.g., with `importlib.resources` as the change note in `setuptools` mentions? https://github.com/pypa/setuptools/commit/530d11498af526c4210d8eeaa1ed6c63f44a390f