[solutionchecker] The CI now throws an error if solution/exercise has not been...

[solutionchecker] The CI now throws an error if solution/exercise has not been updated while the other one has.

.patches/apply_patches.sh

@@ -21,6 +21,6 @@ do
     echo "The solution for $exerciseName seems to be up to date."
   else
     echo "You forgot to update the exercise or the solution for $exerciseName!"
-    exit
+    exit 1
   fi
 done