add num_samples to results_dict in EvaluationTracker.save()

Author: itsmejul

src/lighteval/logging/evaluation_tracker.py

@@ -229,6 +229,7 @@ def save(self) -> None:
             "config_tasks": self.task_config_logger.tasks_configs,
             "summary_tasks": self.details_logger.compiled_details,
             "summary_general": asdict(self.details_logger.compiled_details_over_all_tasks),
+            "num_samples": self.calculate_num_samples(),
         }
 
         # Create the details datasets for later upload