List tags nobody has pulled in 90 days

from datetime import datetime, timedelta, timezone
from clickruntime import on_trigger, credentials, http, notify

NAMESPACE = "acme"
HUB = "https://hub.docker.com/v2"

@on_trigger
def run(event):
    token = http.post(f"{HUB}/auth/token", json={"identifier": NAMESPACE,
                      "secret": credentials.secret("DOCKER_HUB_TOKEN")}).json()["access_token"]
    headers = {"Authorization": f"Bearer {token}"}
    cutoff = (datetime.now(timezone.utc) - timedelta(days=90)).isoformat()
    repos = http.get(f"{HUB}/namespaces/{NAMESPACE}/repositories", params={"page_size": 100},
                     headers=headers).json()["results"]
    lines, total = [], 0
    for r in repos:
        tags = http.get(f"{HUB}/namespaces/{NAMESPACE}/repositories/{r['name']}/tags",
                        params={"page_size": 100}, headers=headers).json()["results"]
        stale = [t for t in tags if not t.get("tag_last_pulled") or t["tag_last_pulled"] < cutoff]
        if stale:
            total += len(stale)
            lines.append(f"{r['name']}:")
            lines += [f"  {t['name']}  last pulled {(t.get('tag_last_pulled') or 'never')[:10]}" for t in stale]
    notify.email_me(f"{total} Docker Hub tags not pulled in 90 days", "\n".join(lines) or "No stale tags.")
    return {"stale": total}