fix: correct suppression of dd output

setup

@@ -85,7 +85,7 @@ echo "    user:" >> tmp
 echo "        registration: false" >> tmp
 echo "        password_reset: false" >> tmp
 
-docker exec -i $KIMAI_CONTAINER_NAME dd of=/opt/kimai/config/packages/local.yaml < tmp >> /dev/null
+docker exec -i $KIMAI_CONTAINER_NAME dd of=/opt/kimai/config/packages/local.yaml < tmp >> /dev/null 2>&1
 
 rm -f tmp