Django 2.2 and 3.0 don't support settings samesite='None' in
HttpResponse.set_cookie() so fix is not necessary and will not be
backported.
Backport of 9bc8b1ad2d88209bf45f389fe3cc8b94909b0e72 from master
Cookies with the "SameSite" flag set to None and without the "secure"
flag will be soon rejected by latest browser versions.
This affects sessions and messages cookies.
Backport of 240cbb63bf9965c63d7a3cc9032f91410f414d46 from master