Я изменил свой asgi.py на такой и всё заработало:
import os
from django.core.asgi import get_asgi_application
from channels.routing import ProtocolTypeRouter, URLRouter
from django.urls import path
os.environ.setdefault('DJANGO_SETTINGS_MODULE', 'climbing_tinder.settings')
django_asgi_app = get_asgi_application()
from finder import consumers
application = ProtocolTypeRouter({
"http": django_asgi_app,
"websocket": URLRouter([
path("ws/notifications/", consumers.NotificationConsumer.as_asgi()),
])
})
