response.set_cookie('cookie_key', secure=True, httponly=True, samesite='Strict', max_age=1800)

Above code in python-flask ensures that the cookie is sent over a secure https connection only and prevents cross scripting attacks to some extent. The issue I get while developing is iceweasel-uxp shows 127.0.0.1:5000 is untrustworthy since it isn't encrypted for development testing.

response.set_cookie('cookie_key', httponly=True, samesite='Strict', max_age=1800)

Above code works well. My question is
Is there a development mode in iceweasel-uxp OR how do I make 127.0.0.1:5000 a trusted address?