Fix readinto typehint (#34444)

Author: vincenttran-msft

sdk/storage/azure-storage-blob/CHANGELOG.md

@@ -13,6 +13,7 @@ tokens to be used with multiple services. By default, the SAS token service scop
 Python 3.12.
 - Fixed an issue where authentication errors could raise `AttributeError` instead of `ClientAuthenticationError` when
 using async OAuth credentials.
+- Fixed an typing issue which incorrectly typed the `readinto` API. The correct input type is `IO[bytes]`.
 
 ## 12.19.0 (2023-11-07)
 

sdk/storage/azure-storage-blob/azure/storage/blob/_download.py

@@ -699,10 +699,10 @@ def content_as_text(self, max_concurrency=1, encoding="UTF-8"):
         self._encoding = encoding
         return self.readall()
 
-    def readinto(self, stream: IO[T]) -> int:
+    def readinto(self, stream: IO[bytes]) -> int:
         """Download the contents of this file to a stream.
 
-        :param IO[T] stream:
+        :param IO[bytes] stream:
             The stream to download to. This can be an open file-handle,
             or any writable stream. The stream must be seekable if the download
             uses more than one parallel connection.

sdk/storage/azure-storage-blob/azure/storage/blob/aio/_download_async.py

@@ -605,10 +605,10 @@ async def content_as_text(self, max_concurrency=1, encoding="UTF-8"):
         self._encoding = encoding
         return await self.readall()
 
-    async def readinto(self, stream: IO[T]) -> int:
+    async def readinto(self, stream: IO[bytes]) -> int:
         """Download the contents of this blob to a stream.
 
-        :param IO[T] stream:
+        :param IO[bytes] stream:
             The stream to download to. This can be an open file-handle,
             or any writable stream. The stream must be seekable if the download
             uses more than one parallel connection.