[gcr/nielsdg/install-gcr-gtk4-header] meson: Make sure we install gcr-gtk4.h

[Niels De Graef <nielsdg src gnome org>]

commit 67811e7d3931e72d17c17d3705e0e3494cfd14b6
Author: Niels De Graef <nielsdegraef gmail com>
Date:   Sat May 28 15:14:04 2022 +0200

    meson: Make sure we install gcr-gtk4.h
    
    Fixes: https://gitlab.gnome.org/GNOME/gcr/-/issues/95

 gcr-gtk4/meson.build | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/gcr-gtk4/meson.build b/gcr-gtk4/meson.build
index a351f2f2..c2562151 100644
--- a/gcr-gtk4/meson.build
+++ b/gcr-gtk4/meson.build
@@ -9,6 +9,7 @@ gcr_gtk4_private_sources = files(
 )
 
 gcr_gtk4_headers = files(
+  'gcr-gtk4.h',
   'gcr-certificate-widget.h',
 )