Add type: ignore for aiofiles to make mypy happier (#1072)

* Add type: ignore to make mypy happier

* Tentatively ignore type checking failure until the following patch gets merged

python/typeshed#4650

starlette/responses.py

@@ -22,8 +22,8 @@
     import aiofiles
     from aiofiles.os import stat as aio_stat
 except ImportError:  # pragma: nocover
-    aiofiles = None
-    aio_stat = None
+    aiofiles = None  # type: ignore
+    aio_stat = None  # type: ignore
 
 try:
     import ujson
@@ -312,7 +312,10 @@ async def __call__(self, scope: Scope, receive: Receive, send: Send) -> None:
         if self.send_header_only:
             await send({"type": "http.response.body", "body": b"", "more_body": False})
         else:
-            async with aiofiles.open(self.path, mode="rb") as file:
+            # Tentatively ignoring type checking failure to work around the wrong type
+            # definitions for aiofile that come with typeshed. See
+            # https://github.com/python/typeshed/pull/4650
+            async with aiofiles.open(self.path, mode="rb") as file:  # type: ignore
                 more_body = True
                 while more_body:
                     chunk = await file.read(self.chunk_size)