Automatic deployment

[martukas]

Upon merge of new code to main branch, the website should be redeployed on the server automatically. Not sure what the best way to do this is and it may depend on what hosting we use for the website in the end.

[martukas]

We might also want to figure out a way to deploy to an alternative URL when not on main, for example - to test a PR. But of course we cannot have an arbitrary number of instances deployed simultaneously, so this may only be semi-automated somehow?