fix: 🐛 remove the "required" constraint on created_at in Lock
the code does not rely on always having a created_at field. And it's not that easy to always ensure it's filled (see `update(upsert=True, ...`)
fix: 🐛 remove the "required" constraint on created_at in Lock: the code does not rely on always having a created_at field. And it's not that easy to always ensure it's filled (see `update(upsert=True, ...`)