Fixing SIMBA max recursion depth error

Co-authored-by: Krista Opsahl-Ong <krista.opsahl-ong@databricks.com>

Author: okhat

dspy/teleprompt/simba.py

@@ -310,7 +310,7 @@ def register_new_program(prog: dspy.Module, score_list: list[float]):
                 trial_logs[idx_prog-1]["train_score"] = avg_score
 
         best_idx = scores.index(max(scores)) if scores else 0
-        best_program = candidate_programs[best_idx]
+        best_program = candidate_programs[best_idx].deepcopy()
         logger.info(
             f"Final trainset scores: {scores}, Best: {max(scores) if scores else 'N/A'} "
             f"(at index {best_idx if scores else 'N/A'})\n\n\n"