otutil: Correctly add ref to bytes when creating GVariant

This one went undiscovered for a while because it turned out we
weren't using it...

src/libotutil/ot-variant-utils.c

@@ -280,6 +280,7 @@ ot_variant_new_from_bytes (const GVariantType  *type,
 #else
   gsize size;
   gconstpointer data = g_bytes_get_data (bytes, &size);
+  g_bytes_ref (bytes);
   return g_variant_new_from_data (type, data, size, trusted,
                                   (GDestroyNotify)g_bytes_unref, bytes);
 #endif