All contribution will now require PRs and peer review

[asim]

We're adding more maintainers to the project. With that all contributions will now go through PRs and require one other person to approve. Most likely it's just me signing off on things but it's just to ensure we're not throwing stuff in for the sake of it but actually thinking about the long term implications. Changes, additional features, etc increase the surface area and complexity and we're working towards v5 design so something to think about.