add missing url_for https schema

src/forest/auth/routes.py

@@ -14,6 +14,7 @@ from models import db, User
 
 from io import BytesIO
 import pyqrcode
+import sys
 
 @auth.route('/authorize/<provider>')
 def oauth2_authorize(provider):
@@ -74,7 +75,7 @@ def oauth2_callback(provider):
         'code': request.args['code'],
         'grant_type': 'authorization_code',
         'redirect_uri': url_for('auth.oauth2_callback', provider=provider,
-                                _external=True),
+                                _external=True, _scheme='https'),
     }, headers={'Accept': 'application/json'})
     if response.status_code != 200:
         print('oauth response code is not 200', file=sys.stderr)