Add `SolidErrors::migrated?` to ensure that automatically updated dependencies fail when missing migrations

[Marcus Riemer]

I just noticed that the upcoming version will require a database migration. I have no idea on how you are planning to communicate or handle the execution of those migrations, but I can point to an implementation that I really like: good_job does a great job on explaining itself with regards to updates.

The most interesting part for me is as follows:

Database migrations introduced in minor releases are not required to be applied until the next major release. If you would like to apply newly introduced migrations immediately, assert GoodJob.migrated? in your application's test suite.

Would you consider something similar for solid_errors?

[Stephen Margheim]

I have released 0.4.0. There is an upgrade guide: https://github.com/fractaledmind/solid_errors/blob/main/UPGRADE.md

But nothing more advanced than that.

I'd be open to exploring something similar to GoodJob, but I think an initial PR would help to see the vision more concretely.