jsonschema needs six>=1.11.0

Version and requirements information containing six:
  [versions] constraint on six: 1.10.0
  Requirement of mock==2.0.0: six>=1.9
  Requirement of slapos.core==1.4.11: six
  Requirement of bcrypt==3.1.4: six>=1.4.1
  Requirement of cryptography==2.3.1: six>=1.4.1
  Requirement of jsonschema: six>=1.11.0
  Requirement of manuel: six
  Requirement of cliff: six>=1.9.0
  Requirement of pyOpenSSL>=18.0.0: six>=1.5.2