Add linebreak between each check result (#117)

For better readability.

src/scwidgets/exercise/_widget_code_exercise.py

@@ -667,7 +667,7 @@ def compute_output_to_check(self, *args, **kwargs) -> Check.FunOutParamsT:
     def handle_checks_result(self, results: List[Union[CheckResult, Exception]]):
         self._output.clear_output(wait=True)
         with self._output:
-            for result in results:
+            for i, result in enumerate(results):
                 if isinstance(result, Exception):
                     raise result
                 elif isinstance(result, CheckResult):
@@ -681,6 +681,9 @@ def handle_checks_result(self, results: List[Union[CheckResult, Exception]]):
                         print(result.message())
                 else:
                     print(result)
+                # add linebreak if not end
+                if i != len(results):
+                    print()
 
     def handle_save_result(self, result: Union[str, Exception]):
         self._output.clear_output(wait=True)