Use github actions to automate push from Devbranch to Master.

[se5a]

As on the tin,
We'd need to improve our testing, eg maybe write some more stable integration tests, and have it do it on passing those tests only.
Problem with our (and any) unit tests is they tend to be very fragile with refactors etc.

I want to keep most our work on dev branch so the pressure to have everything perfect before pushing is low, but keep Master a bit tighter.