Limit changelog for pre-releases

[jzaefferer]

trafficstars

Would be nice if the changelog only included commits from one pre-release to the next, instead of all from the previous stable release to the current pre-release.

[scottgonzalez]

I think this is just a matter of updating the logic for what the previous version is. Right now for new minor versions, we check for versions in the previous minor family (see https://github.com/jquery/jquery-release/blob/4b207e8d80bce4c1e6462d2ee4d0553a8194e241/lib/repo.js#L181-L185). We can instead search for pre-releases in the new minor family. If we don't find any, fall back to the current logic.

Since pre-releases can exist for any type of release (major, minor, patch), we'd need to implement this logic for each of those.