Update flake8 from 3.9.2 to 4.0.1

Author: pyup-bot

requirements.txt

@@ -1,6 +1,6 @@
 ansible-lint==4.3.0
 docker==5.0.3
-flake8==3.9.2
+flake8==4.0.1
 molecule==3.0.8
 pytest==6.2.5
 testinfra==6.0.0