Update deprecated type hinting in platform, plugins, triton_utils, vllm_flash_attn (#18129)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

vllm/plugins/__init__.py

@@ -2,7 +2,7 @@
 
 import logging
 import os
-from typing import Callable, Dict
+from typing import Callable
 
 import torch
 
@@ -14,7 +14,7 @@ logger = logging.getLogger(__name__)
 plugins_loaded = False
 
 
-def load_plugins_by_group(group: str) -> Dict[str, Callable]:
+def load_plugins_by_group(group: str) -> dict[str, Callable]:
     import sys
     if sys.version_info < (3, 10):
         from importlib_metadata import entry_points