Update sys.rst

Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>

Author: pablogsal

Doc/library/sys.rst

@@ -1854,7 +1854,7 @@ always available. Unless explicitly noted otherwise, all variables are read-only
    local and remote interpreters must be the same exact version.
 
    .. availability:: Unix, Windows.
-   .. versionadded:: 3.14
+   .. versionadded:: next
 
 
 .. function:: _enablelegacywindowsfsencoding()