Fix typo; open_id => openid
Fix typo; open_id => openid

According to https://auth0.com/docs/protocols it's "openid"
ignaciojonas/ruby-auth0,ignaciojonas/ruby-auth0,ChuckJHardy/ruby-auth0,auth0/ruby-auth0,auth0/ruby-auth0,ChuckJHardy/ruby-auth0,ignaciojonas/ruby-auth0