fix(cron): Fixed cron jobs being consumed by multiple workers

Because of how the consume cron query is built, it is possible for
multiple workers to attempt to consume the same cron job at the same
time. This tweaks the query such that only a single worker should be
able to consume the cron job now.

server/background/postgres.go

@@ -668,7 +668,7 @@ func (p *postgresJobProcessor) consumeCronMaybe(queue string, next time.Time) (*
 	subQuery := p.db.ModelContext(ctx, new(models.CronJob)).
 		Column("queue").
 		Where(`"queue" = ?`, queue).
-		Where(`"next_run_at" <= ?`, next).
+		Where(`"next_run_at" < ?`, next).
 		For(`UPDATE SKIP LOCKED`).
 		Limit(1)