fix: filter for upcoming events in #dashboard

In ac423bb, we implemented eager_load but unfortunately dropped the `upcoming` method. This change puts it back.

Signed-off-by: jonathan.kerr <3410350+jonodrew@users.noreply.github.com>

Author: jonodrew

app/controllers/dashboard_controller.rb

@@ -87,7 +87,8 @@ def total_upcoming_events_count
   end
 
   def upcoming_events_for_user
-    chapter_workshops = Workshop.eager_load(:chapter, :sponsors, :organisers, :permissions)
+    chapter_workshops = Workshop.upcoming
+                                .eager_load(:chapter, :sponsors, :organisers, :permissions)
                                 .where(chapter: current_user.chapters)
                                 .to_a