warn users of poor semantic versioning when publishing

Dart dependency resolution leans heavily on semantic versioning to ensure that a package is compatible.

The problem ,as a publisher, is correctly identifying the right semantic version no. when publishing

The result is that on more than one occasion I've released a package that breaks the semantic rules and therefore breaks dependant packages.

It would be useful if when publishing a package pub.dev checked to see if the selected semantic version match the api changes.

I've not spent a lot of time thinking about this but I suspect that in many cases its fairly easy to detect a break in an api.

New api's could be ignored. New named and optional parameters (in the right order) could also be ignored.

This should probably be a warning.

I would guess this is a fair amount of work but it feels like a an exercise that would improve the reliability of the dart ecosystem.