This is one of the most requested features in 5e in general. Luckily in 5.5e (not BG3) they are planning to make the warlock work with any mental stat.
Now that I think about it, we saw today some screen of the the blade pact the description talks about "your spellcasting stat", not "CHA". It might be just wording though.
Anyways, Eldritch knight and Arcane Trickster, subclasses of fighter and rogue, are INT caster's too.
