Don't log if path starts with /static/

runserver_quiet.py

from django.core.servers.basehttp import WSGIRequestHandler

# Grab the original log_message method.
_log_message = WSGIRequestHandler.log_message

def log_message(self, *args):
    # Don't log if path starts with /static/
    if self.path.startswith("/static/"):
        return
    else:
        return _log_message(self, *args)

# Replace log_message with our custom one.
WSGIRequestHandler.log_message = log_message

# Import the original runserver management command
from django.core.management.commands.runserver import Command

Hat tip https://code.djangoproject.com/ticket/25704