fix(deps): update typescript-eslint monorepo to v3 (major)

[JustinBeckwith]

No description provided.

[alexander-fenster]

Unrelated to this change, I think it would make perfect sense to have a baseline-kind of tests for gts - a random code that gets formatted and compared to the checked in baseline. That way we would catch if a random eslint or config change triggers any incompatibility in formatting.