tests: Fix a free function in the GIO tests
tests: Fix a free function in the GIO tests

The monitor_path comes from g_file_get_path(), so should be freed with
g_free() rather than free(). This makes no difference because they are
the same function in practice, but using free() is a bit confusing.

Signed-off-by: Philip Withnall <29c2a2ac2a854b9cf047275aa9de346d096be2e0@endlessm.com>
Reviewed-by: nobody

endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib