[BE] Use Literal from typing (pytorch#98846)

Since PyTorch is Python-3.8+ compatible framework

Pull Request resolved: pytorch#98846
Approved by: https://github.com/janeyx99, https://github.com/ZainRizvi, https://github.com/Neilblaze

Author: malfet

torchgen/dest/register_dispatch_key.py

@@ -1,9 +1,7 @@
 import itertools
 import textwrap
 from dataclasses import dataclass
-from typing import List, Optional, Tuple, Union
-
-from typing_extensions import Literal  # Python 3.8+
+from typing import List, Literal, Optional, Tuple, Union
 
 import torchgen.api.cpp as cpp
 import torchgen.api.meta as meta

torchgen/gen.py

@@ -10,6 +10,7 @@
     Callable,
     Dict,
     List,
+    Literal,
     Optional,
     Sequence,
     Set,
@@ -19,7 +20,6 @@
 )
 
 import yaml
-from typing_extensions import Literal  # Python 3.8+
 
 import torchgen.api.dispatcher as dispatcher
 import torchgen.api.meta as meta

torchgen/utils.py

@@ -16,6 +16,7 @@
     Iterable,
     Iterator,
     List,
+    Literal,
     NoReturn,
     Optional,
     Sequence,
@@ -25,8 +26,6 @@
     Union,
 )
 
-from typing_extensions import Literal  # Python 3.8+
-
 from torchgen.code_template import CodeTemplate
 
 # Safely load fast C Yaml loader/dumper if they are available