Remove fetch-depth: 0 requirement

[tombruijn]

Either do something like fetch-depth: ${{github.event.push.commits}} that doesn't break for the pull_request event and others.

Possibly: fetch-depth: ${{github.event.push.commits || github.event.pull_request.commits}} if that works.

And for the pull_request event I guess I could run git fetch origin ${{github.event.pull_request.base.ref}} in the action itself.

Or even git fetch --shallow-exclude=base/${{github.event.pull_request.base.ref}}^