Add GitHub Actions CI

[kristapsk]

Resolves #13.

[kristapsk]

Still need to figure out how to make it work both from a branch and pull request. Main issue is fetching tags, otherwise semver check (7dc1f63) will fail. Couldn't make it work using GitHub checkout action.

[x1ddos]

looks like this fails before tags and anything else, at the checkout step:

isn't it supposed to use a github actions/checkout@v4 instead of a manual git clone ...? see https://github.com/actions/checkout

[kristapsk]

isn't it supposed to use a github actions/checkout@v4 instead of a manual git clone ...? see https://github.com/actions/checkout

See my comment above, couldn't get fetching tags using checkout action and that made semver check to fail.

But now I couldn't get it work both from a branch and in a PR. Will get back to this and try to fix, hopefully soon.