binhex: improve bytes handling (#9035)

stdlib/binhex.pyi

@@ -1,3 +1,4 @@
+from _typeshed import _BufferWithLen
 from typing import IO, Any
 from typing_extensions import Literal, TypeAlias
 
@@ -27,9 +28,9 @@ class openrsrc:
 
 class BinHex:
     def __init__(self, name_finfo_dlen_rlen: _FileInfoTuple, ofp: _FileHandleUnion) -> None: ...
-    def write(self, data: bytes) -> None: ...
+    def write(self, data: _BufferWithLen) -> None: ...
     def close_data(self) -> None: ...
-    def write_rsrc(self, data: bytes) -> None: ...
+    def write_rsrc(self, data: _BufferWithLen) -> None: ...
     def close(self) -> None: ...
 
 def binhex(inp: str, out: str) -> None: ...