Fix compatibility with omniauth-oauth2 >= v1.4

[pboling]

Fix for breaking change introduced in omniauth-oauth2 v1.4.0

• omniauth/omniauth-oauth2@2615267
• Don't override callback_url Attempt to correct #28 omniauth/omniauth-oauth2#70

[pboling]

@NickMeves This gem is not compatible with current omniauth-oauth2 gem, which is a security problem, so letting you know as you appear to be a security engineer at Greenhouse.

[NickMeves]

@NickMeves This gem is not compatible with current omniauth-oauth2 gem, which is a security problem, so letting you know as you appear to be a security engineer at Greenhouse.

Thanks for the heads up. I forwarded this to the team that owns the codebase.

[NickMeves]

Linking discussion in the other thread for context for the team that picks this up: #9 (comment)