'python_2_unicode_compatible' import fix for Django V3+

[mnislam01]

Since Django V3, Django dropped python_2_unicode_compatible from django.utils.encoding module.
To be compatible with Django 3+ we should import that module from six package.

[coveralls]

Coverage remained the same at 52.381% when pulling 4d1fe12 on mnislam01:dev into 06ab643 on geex-arts:dev.

[raifran1]

O django-jet ainda esta incompatível com o django V3