As of v2.0.0 of this gem, it will require OmniAuth 2.0.0. This is due to changes that came with OmniAuth that required a breaking change in this gem. Because we changed the strategy's code, you should not need to change any omniauth-github specific code.
You should refer to OmniAuth's v2.0.0 release and/or the v2.0 upgrade guide when upgrading OmniAuth to v2.0.