clapper-app: fix adw 1.6 deprecations

src/bin/clapper-app/clapper-app-about-dialog.h

@@ -0,0 +1,29 @@
+/* Clapper Application
+ * Copyright (C) 2024 Rafał Dzięgiel <rafostar.github@gmail.com>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#include <glib.h>
+#include <glib-object.h>
+#include <gtk/gtk.h>
+
+G_BEGIN_DECLS
+
+G_GNUC_INTERNAL
+GtkWidget * clapper_app_about_dialog_new (void);
+
+G_END_DECLS