The flufl.flake8 is not needed to run tests.
https://github.com/python/importlib_metadata/issues/527

--- importlib_metadata-8.7.0/pyproject.toml.orig
+++ importlib_metadata-8.7.0/pyproject.toml
@@ -35,7 +35,6 @@
 	'importlib_resources>=1.3; python_version < "3.9"',
 	"packaging",
 	"pyfakefs",
-	"flufl.flake8",
 	"pytest-perf >= 0.9.2",
 	"jaraco.test >= 5.4",
 ]