Revert WPS flake8 hook version to 4.0.1

Author: webknjaz

.pre-commit-config.yaml

@@ -98,7 +98,7 @@ repos:
 
 - repo: https://github.com/PyCQA/flake8.git
   # NOTE: This is kept at v4 for until WPS starts supporting flake v5.
-  rev: 6.0.0  # enforce-version: 4.0.1
+  rev: 4.0.1  # enforce-version: 4.0.1
   hooks:
   - id: flake8
     alias: flake8-only-wps