[gtk/password-entry-buffer] Install gtkpasswordentrybuffer.h

[Matthias Clasen <matthiasc src gnome org>]

commit 621e0a13e9f923a60b91e01996986765ce4d7b3c
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Jun 8 07:49:06 2021 -0400

    Install gtkpasswordentrybuffer.h

 gtk/meson.build | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/gtk/meson.build b/gtk/meson.build
index 516560a84e..416be43bdc 100644
--- a/gtk/meson.build
+++ b/gtk/meson.build
@@ -604,6 +604,7 @@ gtk_public_headers = files([
   'gtkpaned.h',
   'gtkpapersize.h',
   'gtkpasswordentry.h',
+  'gtkpasswordentrybuffer.h',
   'gtkpicture.h',
   'gtkpopover.h',
   'gtkpopovermenu.h',