This is an error in Python 3.12; fix it by using a raw string literal.

Cc:  <qemu-stable@nongnu.org>
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-ID: <20231108105649.60453-1-marcandre.lureau@redhat.com>