project: Switch to libhandy-1

This commit updates the dependencies for libhandy to the tagged 1.0
release and changes the code to accomodate the changes from
libhandy-0 to libhandy-1.

Notable changes:
edit-dialog: HdyDialog has been dropped in [1]
alarm-row: action child type in HdyActionRow has been removed.

[1] https://gitlab.gnome.org/GNOME/libhandy/-/merge_requests/434

src/gui/gcal-application.c

@@ -34,6 +34,7 @@
 #include <glib-object.h>
 #include <gio/gio.h>
 #include <glib/gi18n.h>
+#include <handy.h>
 
 struct _GcalApplication
 {
@@ -446,6 +447,9 @@ gcal_application_startup (GApplication *app)
   if ((g_application_get_flags (app) & G_APPLICATION_IS_SERVICE) != 0)
     g_application_set_inactivity_timeout (app, 3 * 60 * 1000);
 
+  /*  initialize libhandy */
+  hdy_init();
+
   GCAL_EXIT;
 }