Fix crash while trying to schedule final seminar

Caused by a missing @Transactional annotation.

core/src/main/java/se/su/dsv/scipro/finalseminar/FinalSeminarRespondentServiceImpl.java

@@ -1,5 +1,6 @@
 package se.su.dsv.scipro.finalseminar;
 
+import jakarta.transaction.Transactional;
 import se.su.dsv.scipro.system.AbstractServiceImpl;
 import se.su.dsv.scipro.system.User;
 
@@ -33,6 +34,7 @@ public class FinalSeminarRespondentServiceImpl extends AbstractServiceImpl<Final
     }
 
     @Override
+    @Transactional
     public List<FinalSeminarRespondent> findOrCreate(FinalSeminar finalSeminar) {
         if(finalSeminar.getId() == null) {
             return new ArrayList<>();