Use PEP 570 syntax in stdlib (#11250)

stdlib/urllib/request.pyi

@@ -227,7 +227,8 @@ class ProxyDigestAuthHandler(BaseHandler, AbstractDigestAuthHandler):
 class _HTTPConnectionProtocol(Protocol):
     def __call__(
         self,
-        __host: str,
+        host: str,
+        /,
         *,
         port: int | None = ...,
         timeout: float = ...,