erp5.util: add missing dependency to 'six'

setup.py

@@ -49,6 +49,7 @@ setup(name=name,
       install_requires=[
         'setuptools', # namespaces
         'psutil >= 0.5.0',
+        'six',
       ],
       extras_require={
         'testnode': ['slapos.core', 'xml_marshaller', 'psutil >= 0.5.0'],

[Julien Muchembled]

@rafael Sorry, this should have been done long time ago, the first time we started to use it.

With the big version bump in slapos@ec1cd866, the NEO SR fails and maybe many other.

/cc @bminusl

[Rafael Monnerat]

No problem, trank you. I will re-release it with this minor change, and check if it works.