Re-evaluate dependencies

[colinodell]

I really liked how v1 had no external dependencies. In v2 we opted to pull in some dependencies instead of reinventing the wheel. I think this was a good decision, but do we truly need everything in that dependency tree? Maybe yes, maybe no. Let's explore if it's reasonable to reduce that footprint in any ways that don't negatively impact users or maintainers. (We don't want to just remove things for the sake of removing things). This way involve some major-version-level changes to league/config as well.

We'll either confirm that we have exactly what we want/need, or we'll find areas to make small improvements.