add gh action CI system

[camallen]

use GH actions for CI system and this would replace travis CI system

Totally up to you if you want to adopt GH Actions for CI

[mwalmsley]

I actually already have something very similar set up via Travis? See .travis.yml

Edit - oh, I see, you're using this to test the build action

[mwalmsley]

I think the action is looking too many "zoobot"'s deep

Obtaining file:///home/runner/work**/zoobot/zoobot/zoobot**
ERROR: file:///home/runner/work/zoobot/zoobot/zoobot does not appear to be a Python project: neither 'setup.py' nor 'pyproject.toml' found.

[camallen]

I actually already have something very similar set up via Travis? See .travis.yml

Edit - oh, I see, you're using this to test the build action

More that travis CI has become a troubling place to host your CI system lately. They were bought out and the company that bought them are squeezing all they can out of folks. The CI run times are long and queue times more so. Also they've had security issues lately as well so most folks are moving OSS systems away from them.

This should co-locate the code and CI system to GH and speed up the CI times significantly as well (faster feedback is good)

[mwalmsley]

LGTM.

• Failing on 3.10 is expected, pytorch/tensorflow devs usually lag a little behind the latest python due to (I assume) engineering effort requiredd
• Added build requirement for 3.7, which many academics use

[mwalmsley]

Also, disabling Travis now via Travis UI