stdlib/3/importlib/metadata: add missing "group" attribute to EntryPoint (#3795)

stdlib/3/importlib/metadata.pyi

@@ -12,6 +12,7 @@ if sys.version_info >= (3, 8):
     class EntryPointBase(NamedTuple):
         name: str
         value: str
+        group: str
     class EntryPoint(EntryPointBase):
         def load(self) -> Any: ...  # Callable[[], Any] or an importable module
         @property