fix: update slot start time validation to check against the current day

- Modified the validation logic to ensure that the slot start time is not before the current day, preventing past slots from being created.

src/api/slot/content-types/slot/lifecycles.ts

@@ -40,7 +40,7 @@ export default {
     if (datetime_start) {
       const now = dayjs().tz(DEFAULT_TZ);
       const slotStart = dayjs(datetime_start).tz(DEFAULT_TZ);
-      if (slotStart.isBefore(now, 'minute')) {
+      if (slotStart.isBefore(now, 'day')) {
         throw new Error(ERR_PAST_SLOT);
       }
     }