Use the standard TOXENV var, rather thatn TOX_ENV
Use the standard TOXENV var, rather thatn TOX_ENV

An environment variable TOX_ENV was being used on CI, and then
explicitly passed to tox, which was rather confusing when running tests
locally, since it's extremely similar to tox's TOXENV variable.

jannon/sorl-thumbnail,jannon/sorl-thumbnail,mariocesar/sorl-thumbnail,jazzband/sorl-thumbnail,mariocesar/sorl-thumbnail,jannon/sorl-thumbnail,mariocesar/sorl-thumbnail,jazzband/sorl-thumbnail,jazzband/sorl-thumbnail