fix: update cms4 branch used in requirements

Author: michaeljcollinsuk

tests/requirements/base.txt

@@ -6,5 +6,5 @@ isort
 tox
 
 # Unreleased django-cms 4.0 compatible packages
-https://github.com/django-cms/django-cms/tarball/develop-4#egg=django-cms
+http://github.com/django-cms/django-cms/tarball/release/4.0.1.x#egg=django-cms
 https://github.com/django-cms/djangocms-versioning/tarball/master#egg=djangocms-versioning