fix(utility): fix the FileExistsError when using cache with multiprocess

When using cache with multiprocess, the result will not necessarily stay
true after asserting `os.path.exists(cache_path) == True`.
Add `exist_ok` when calling `os.makedirs` to fix this problem.

PR Closed: #1113

tensorbay/utility/file.py

@@ -190,8 +190,7 @@ def open(self) -> Union[HTTPResponse, BufferedReader]:
 
         if not os.path.exists(cache_path):
             dirname = os.path.dirname(cache_path)
-            if not os.path.exists(dirname):
-                os.makedirs(dirname)
+            os.makedirs(dirname, exist_ok=True)
 
             with self._urlopen() as fp:
                 with open(cache_path, "wb") as cache: