`secure=True` `set_cookie` option for the access token in `cognito_login_callback` may break testing in localhost

[Castdeath97]

This flag seems to cause the access token cookie to be ignored in some browsers:

• https://stackoverflow.com/a/60983003

Changing this line is probably a bad idea security wise, so better just leave a note somewhere about this potential quirk in the README for people facing this issue during local testing purposes.