Add depreciation warning for sys.print_exception

Author: RetiredWizard

docs/library/sys.rst

@@ -17,6 +17,9 @@ Functions
 
 .. function:: print_exception(exc, file=sys.stdout, /)
 
+   This function is being deprecated and will be removed starting in
+   CircuitPython 10.x, `traceback.print_exception()` should be used instead.
+
    Print exception with a traceback to a file-like object *file* (or
    `sys.stdout` by default).