We should enable semver checks on CI

[jasonwilliams]

As we approach 1.0 we should make sure we’re not making breaking changes or at the very least tracking breaking changes that are made intentionally.

To do this we should add a new CI on each PR which runs https://github.com/obi1kenobi/cargo-semver-checks.

We probably want to have a PR ready but enable this after this after the release so we can catch all PRs after.

[thakazuki]

I'd like to work on this issue.
Kindly assign it to me!