Use Python 3.9 syntax in examples (#37279)

Signed-off-by: cyy <cyyever@outlook.com>

examples/pytorch/test_pytorch_examples.py

@@ -1,4 +1,3 @@
-# coding=utf-8
 # Copyright 2018 HuggingFace Inc..
 #
 # Licensed under the Apache License, Version 2.0 (the "License");
@@ -87,7 +86,7 @@ def get_results(output_dir):
     results = {}
     path = os.path.join(output_dir, "all_results.json")
     if os.path.exists(path):
-        with open(path, "r") as f:
+        with open(path) as f:
             results = json.load(f)
     else:
         raise ValueError(f"can't find {path}")