Should treat tool specs as case insensitive

[JohnnyMorganz]

Right now, aftman treats e.g. UpliftGames/[email protected] and upliftgames/[email protected] as separate tools and will install the latter again even if the former is already installed. They should instead be treated as the same tool.

I'm unsure however if there are any negative side effects for it being case insensitive

[LPGhatguy]

Yeah, this is definitely something to fix. We can use manually implement PartialEq and Hash to use lowercase variants of names while preserving the original case.