Fix availability of some constants for Windows (#10818)

stdlib/msvcrt.pyi

@@ -1,8 +1,9 @@
 import sys
-from typing_extensions import Literal
+from typing_extensions import Final, Literal
 
 # This module is only available on Windows
 if sys.platform == "win32":
+    CRT_ASSEMBLY_VERSION: Final[str]
     LK_UNLCK: Literal[0]
     LK_LOCK: Literal[1]
     LK_NBLCK: Literal[2]