Add colon

Author: encukou

courses.yml

@@ -479,7 +479,7 @@ lessons:
   url: https://github.com/tomjelinek/naucse-python
   branch: compiled/2024-brno-zacatecnici
   path: 2024-brno-zacatecnici-cast1
-2024/hradec-snake-jaro
+2024/hradec-snake-jaro:
   url: https://github.com/robrichter/naucse-python
   branch: compiled/hradec-snake-04