Check constraint support

[azz]

Hey there. We currently use annotate_models, looking at maybe switching over, but it seems this fork does not support annotating check constraints. ctran/annotate_models#868

@drwl would you be keen to see a similar implementation here?

[drwl]

@azz thanks for the issue! I added a PR, could you try building that version of the gem and tell me if it works and if you have any feedback?

[lparry]

Hey @drwl, I'm a colleague of @azz, I've had a quick play switching from ctran/annotate_models to annotaterb just now and can confirm that the check constraint annotations appear to work correctly/the same as what we are used to.

There are some other unexpected changes unrelated to check constraints, but is probably down to config we just need to tweak. I will open an issue about the one that has me a bit stumped.

[drwl]

@lparry thanks for taking the time to test it and providing feedback. I'm planning to add some unit tests and merging it in.