platform: fix chaining up finalize() in NMPlatform

This also causes leaks with recent glib, which can be found via valgrind.

Fixes: c7b3862503 ('platform: add network namespace support to platform')
(cherry picked from commit 1a1c22e38c)

src/libnm-platform/nm-platform.c

@@ -8966,6 +8966,8 @@ finalize(GObject *object)
     g_clear_object(&self->_netns);
     nm_dedup_multi_index_unref(priv->multi_idx);
     nmp_cache_free(priv->cache);
+
+    G_OBJECT_CLASS(nm_platform_parent_class)->finalize(object);
 }
 
 static void