False positives when case-insensitive unique indexes have CITEXT strings

[gee-forr]

Hi there,

Thanks for this great gem. It's such a useful tool and we love it.

I noticed that when I run it against a postgres db that has a unique index on a Postgres Case Insensitive Text (CITEXT) string, it still recommends creating an index using the lower(column_name) function.

My understanding is that using a CITEXT field removes the need for using lower() in the index.

@gregnavis Would you be keen on me submitting a PR to avoid this false positive?

[fatkodima]

Your understanding is correct. Please open a PR.