add env vars for default dev server port and host

import os

import sys

from dotenv import load_dotenv

from django.core.management.commands import runserver

load_dotenv()

runserver.Command.default_port = os.getenv("DJANGO_RUNSERVER_PORT") or "8000"

runserver.Command.default_addr = os.getenv("DJANGO_RUNSERVER_ADDR") or "127.0.0.1"

runserver.Command.default_addr_ipv6 = os.getenv("DJANGO_RUNSERVER_ADDR_IPV6") or "::1"

def main():

    """Run administrative tasks."""