Fix typing in client connection initialization.

Author: aaugustin

src/websockets/legacy/client.py

@@ -11,6 +11,7 @@
     Any,
     AsyncIterator,
     Callable,
+    Coroutine,
     Generator,
     List,
     Optional,
@@ -543,7 +544,16 @@ def __init__(
         self.logger = logger
 
         # This is a coroutine function.
-        self._create_connection = create_connection
+        self._create_connection = cast(
+            functools.partial[
+                Coroutine[
+                    Any,
+                    Any,
+                    Tuple[asyncio.BaseTransport, WebSocketClientProtocol],
+                ]
+            ],
+            create_connection,
+        )
         self._uri = uri
         self._wsuri = wsuri
 
@@ -652,7 +662,6 @@ async def __await_impl_timeout__(self) -> WebSocketClientProtocol:
     async def __await_impl__(self) -> WebSocketClientProtocol:
         for redirects in range(self.MAX_REDIRECTS_ALLOWED):
             transport, protocol = await self._create_connection()
-            protocol = cast(WebSocketClientProtocol, protocol)
 
             try:
                 await protocol.handshake(