build: Include Cally in St introspection

CallyActor is exposed indirectly via StAccessible's parent type,
so add the dependency to shut up a gjs warning.

https://bugzilla.gnome.org/show_bug.cgi?id=781471

src/st/meson.build

@@ -142,7 +142,7 @@ libst_gir = gnome.generate_gir(libst,
   sources: st_gir_sources,
   nsversion: '1.0',
   namespace: 'St',
-  includes: ['Clutter-' + mutter_api_version, 'Gtk-3.0'],
+  includes: ['Clutter-' + mutter_api_version, 'Cally-' + mutter_api_version, 'Gtk-3.0'],
   dependencies: [mutter_dep],
   include_directories: include_directories('..'),
   extra_args: ['-DST_COMPILATION', '--quiet'],