fix: use explicit UTF-8 encoding when writing code_interpreter temp script (#3023)

Co-authored-by: octo-patch <octo-patch@github.com>

packages/dbgpt-app/src/dbgpt_app/openapi/api_v1/agentic_data_api.py

@@ -1698,7 +1698,7 @@ print(json.dumps(summary, ensure_ascii=False))
 
         try:
             tmp_path = os.path.join(work_dir, "_run.py")
-            with open(tmp_path, "w") as tmp:
+            with open(tmp_path, "w", encoding="utf-8") as tmp:
                 tmp.write(full_code)
 
             proc = await asyncio.create_subprocess_exec(