[Feature request] Add regex operator

[roniemartinez]

Using startswith becomes a challenge when you have a very long list. This could be simplified with a regex support.

Django supports __regex and __iregex: https://docs.djangoproject.com/en/5.0/ref/models/querysets/#regex

It seems that this has been discussed in #47 (comment)

[mattcousins]

This would be useful for me.