fix: slot reservation uses wrong event length (#10103)

Co-authored-by: CarinaWolli <wollencarina@gmail.com>

packages/trpc/server/routers/viewer/slots/util.ts

@@ -277,7 +277,7 @@ export async function getSchedule(input: TGetScheduleInputSchema) {
   );
   const workingHours = getAggregateWorkingHours(userAvailability, eventType.schedulingType);
   const availabilityCheckProps = {
-    eventLength: eventType.length,
+    eventLength: input.duration || eventType.length,
     currentSeats,
   };