fix minor bug, message variable does not exist (#46777)
Summary:
When run with `--continue-through-error`, the script ends with the following error:
```
Traceback (most recent call last):
File "run_test.py", line 745, in <module>
main()
File "run_test.py", line 741, in main
print_to_stderr(message)
NameError: name 'message' is not defined
make: *** [macos-compat] Error 1
```
This PR just changes `message` to `err`, which is the intended variable.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/46777
Reviewed By: seemethere
Differential Revision: D24510460
Pulled By: janeyx99
fbshipit-source-id: be1124b6fc72b178d62acc168d0cbc74962de52b
