Upgrade sinatra_auth_github to v2.0.0
Upgrade sinatra_auth_github to v2.0.0

This allows us to use Sinatra v2.0.
https://github.com/atmos/sinatra_auth_github/compare/v1.2.0...v2.0.0

benbalter/squad_goals,benbalter/squad_goals,benbalter/squad_goals