fix: windows platform gbk codec bug

Author: zakahan

veadk/evaluation/base_evaluator.py

@@ -199,7 +199,7 @@ def build_eval_set(self, file_path: str):
         eval_case_data_list: list[EvalTestCase] = []
 
         try:
-            with open(file_path, "r") as f:
+            with open(file_path, "r", encoding="utf-8") as f:
                 file_content = json.load(f)
         except json.JSONDecodeError as e:
             raise ValueError(f"Invalid JSON format in file {file_path}: {e}")