[System] UserController: Passwords should be strings

* Even the inital dummy password

flaschengeist/controller/userController.py

@@ -179,7 +179,7 @@ def register(data):
     user = User(**values)
     set_roles(user, roles)
 
-    password = secrets.token_bytes(16)
+    password = secrets.token_urlsafe(16)
     current_app.config["FG_AUTH_BACKEND"].create_user(user, password)
     db.session.add(user)
     db.session.commit()