SocialLogin: tighten types of abstract interfaces
SocialLogin: tighten types of abstract interfaces

The base classes for League\OAuth2 loosen the return types in the
abstract interfaces used by the providers (Google, Facebook, etc.),
but we need the more specific types.

See https://github.com/thephpleague/oauth2-client/issues/897.

hemberger/smr,hemberger/smr,smrealms/smr,smrealms/smr,hemberger/smr,hemberger/smr,smrealms/smr