Revise the PR template

[matrss]

Noone is actually fully adhering to what the PR template asks of PRs. It asks twice for the associated issue and if the PR is a breaking change, and suggests a naming scheme that doesn't reflect the lived reality.

I think it can be condensed to something much shorter, and if we really want to follow conventional commits for PR titles, as the template suggests, we should make that a criteria for code review. Or just drop it from the template if not.