week-view: fix active and current date handling

The active date is the visible date, while the current date
is today. We shouldn't confuse those two.

src/views/gcal-week-header.c

@@ -857,6 +857,7 @@ gcal_week_header_finalize (GObject *object)
   GcalWeekHeader *self = GCAL_WEEK_HEADER (object);
   gint i;
 
+  g_clear_pointer (&self->active_date, g_free);
   g_clear_pointer (&self->current_date, g_free);
 
   for (i = 0; i < 7; i++)