We do not need to check sources for this project.

--- immutables-0.21/pyproject.toml.orig
+++ immutables-0.21/pyproject.toml
@@ -33,12 +33,7 @@
 
 [project.optional-dependencies]
 # Minimal dependencies required to test immutables.
-# pycodestyle is a dependency of flake8, but it must be frozen because
-# their combination breaks too often
-# (example breakage: https://gitlab.com/pycqa/flake8/issues/427)
 test = [
-    'flake8~=5.0',
-    'pycodestyle~=2.9',
     'pytest~=7.4',
 ]