Merge branch 'renovate/cffi-1.x' into 'master'

Update dependency cffi to v1.15.0

See merge request openappstack/openappstack!541

requirements.txt

@@ -20,7 +20,7 @@ certifi==2021.10.8
     # via
     #   kubernetes
     #   requests
-cffi==1.14.6
+cffi==1.15.0
     # via
     #   bcrypt
     #   cryptography