fix: Don't quote uppercase strings

[max-sixty]

This is a temporary workaround for @mklopets & team, while we resolve #820.

@aljazerzen -- not sure if you think this is an acceptable tradeoff? I'll wait for your review.

[max-sixty]

Sounds like @mklopets already has a workaround, so maybe this isn't worth merging.

But @mklopets if it's 5x easier to change something in PRQL than your lib, then fine to change it in PRQL, even if it's not in the right direction for a narrow definition of correctness.

[aljazerzen]

As I said on discord, I would prefer if PRQL would remain case sensitive.

[max-sixty]

As I said on discord, I would prefer if PRQL would remain case sensitive.

OK, given @mklopets has a workaround to the s-string issue, I'm closing