Improve CI

[akkashk]

• Remove Travis CI
• Tidy up circle CI file
• Add support for black formatting

[akkashk]

@dunckerr PR is ready for review, I've split the changes into self-contained commits since I'm reformatting a lot of files as part of black changes

[bmoscon]

I thought in the past someone tried a massive reformatting of everything similar to this (maybe it was using black, maybe not, was years ago) and we opted to not accept it because it made a lot of changes that polluted the change history/blame for little gain. What is the reason behind this change? @jamesblackburn I believe you were involved in the past ticket/PR to which I am referring.

[dunckerr]

@akkashk I agree with Bryant - can we add the black code to .circleci but comment it out for now? if we're going to do the black reformat we should do it with 1 commit and when everyone is happy.

Second question - does $VERSION get passed into the the individual build sections at the bottom of the file? I thought you said that was broken and I cant see how you fixed it?

[bmoscon]

I'm not opposed to circle, but why not use github actions? They seem much more powerful and flexible than anything I've seen on Travis or Circle

[akkashk]

Happy to remove my commit with black changes.

does $VERSION get passed into the the individual build sections at the bottom of the file

@dunckerr before we were setting the env var $VERSION in a separate step and writing it to the file in a different step. Now it's all done as part of the same step which should fix the issue

[akkashk]

I'm not opposed to circle, but why not use github actions?

Don't have a strong preference. Our other open source projects use circleci and it's nice being able to share some CI config code between them.