Following the lead from tox, use a simple Python script instead of depending
on ``invoke``.
Other changes:
* Some colors using ``colorama``.
* Run ``pre-commit`` before the final commit to ensure everything is neatly
formatted.
* Drop generating local tag: legacy from the time we used ``devpi`` as staging
area, currently we no longer use it, and we should push a
tag from the last HEAD of the PR always to ensure it is correct.
Anthony Sottile
Bruno Oliveira