Next release (brack3t#257)

* Update README.md
  Updates Supported Django Versions section.

* Tox now only tests recent Pythons and Djangos

* Include necessary files to build docs in source tarball. Closes brack3t#250

* Fixes deprecated imports, adds `six` as requirement

* force text to prevent Python 2 unicode fun

* Added --nomigrations option to pytest
  For some reason this makes the tests work on my machine
  (thanks Baptiste!)

* Have to specify a non-breaking version of semantic-version (lol)

* Update CONTRIBUTORS.txt

* Release date

Co-authored-by: Steve Bywater <[email protected]>
Co-authored-by: Baptiste Mispelon <[email protected]>

Bump version: 1.12.0 → 1.13.0

add bumpversion configuration

version bump

release updates

readme update

[ci skip]

readme update

[ci skip]

added 145 to changelog

added 145 to changelog

date change