[gtk/matthiasc/for-master] inspector: Plug another memory leak

[Matthias Clasen <matthiasc src gnome org>]

commit 0e6eba3968676ad6b9d76ee2403406ad6fedf9ac
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Sep 1 13:06:20 2020 -0400

    inspector: Plug another memory leak
    
    Fixes: #3107

 gtk/inspector/gtktreemodelcssnode.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/gtk/inspector/gtktreemodelcssnode.c b/gtk/inspector/gtktreemodelcssnode.c
index e6d87dc985..2939e438cf 100644
--- a/gtk/inspector/gtktreemodelcssnode.c
+++ b/gtk/inspector/gtktreemodelcssnode.c
@@ -345,6 +345,8 @@ gtk_tree_model_css_node_finalize (GObject *object)
       priv->root = NULL;
     }
 
+  g_free (priv->column_types);
+
   G_OBJECT_CLASS (gtk_tree_model_css_node_parent_class)->finalize (object);
 }