fix: use correct gi-docgen reference

Apparently this is, or always was, `GObject.Type` rather than
`GLib.Type` as one would expect, were they the sort for run-on
sentences and the like.

src/libvalent/core/valent-component.c

@@ -566,7 +566,7 @@ valent_component_class_init (ValentComponentClass *klass)
   /**
    * ValentComponent:plugin-type:
    *
-   * The extension point [alias@GLib.Type].
+   * The extension point [alias@GObject.Type].
    *
    * Since: 1.0
    */