Vanderlei Sbaraini Amancio

Changing line 35 in file `socialiteproviders/manager/src/Oauth2/AbstractProvider` from `getAccessTokenResponse` to `getAccessToken` I manage to get Gitlab Provider pass this phase, but it does not work anyway, because Gitlab returns a 401...

@edbizarro checkout #166 ! I've got it working after following the steps presented in that issue.