Use email_provider? at sync_uid (#1243)

Author: ihatov08

app/models/devise_token_auth/concerns/user_omniauth_callbacks.rb

@@ -23,6 +23,6 @@ def email_provider?
   end
 
   def sync_uid
-    self.uid = email if provider == 'email'
+    self.uid = email if email_provider?
   end
 end