Add support for Flipt provider

[gaby]

i've been reading about Openfeature and noticed that some of the languages already have a Flipt provider but the Python SDK is missing one.

Example of the Golang one: https://github.com/open-feature/go-sdk-contrib/tree/main/providers/flipt

[markphelps]

Hi @gaby from Flipt! We can definitely prioritize a python open feature provider!

In the meantime, we did implement Open Feature Remove Eval Protocol and there looks to be a Python OFREP provider so perhaps that would be another avenue?

[gaby]

@markphelps Yes that could probably work (the conrrib)

Also saw this PR #88 not sure if it also helps with this ticket.

Thanks!