[gtksourceview] view: plug leak of background color string

[Christian Hergert <chergert src gnome org>]

commit 004fbb68e8a6fec58acd1b6708abc0da7d1b0571
Author: Christian Hergert <chergert redhat com>
Date:   Tue Jun 22 11:12:32 2021 -0700

    view: plug leak of background color string

 gtksourceview/gtksourceview.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/gtksourceview/gtksourceview.c b/gtksourceview/gtksourceview.c
index bce70298..462831cb 100644
--- a/gtksourceview/gtksourceview.c
+++ b/gtksourceview/gtksourceview.c
@@ -4741,6 +4741,7 @@ update_right_margin_colors (GtkSourceView *view)
                        }
 
                        g_clear_pointer (&color_str, g_free);
+                       g_clear_pointer (&text_background_str, g_free);
                }
        }