testsuite: Fix notify test no not fail on the 30th

We are setting the month property to 10 different values,
checking that the change succeeds. But the calendar defaults
to the current date, so on every 30th of the month, we
try to set a date of Febuary 30, which fails.

Lets fix this before the 31st, by setting the calendar
to a good date.

testsuite/gtk/notify.c

@@ -465,6 +465,15 @@ test_type (gconstpointer data)
                                NULL);
       g_object_unref (list_store);
     }
+  else if (g_type_is_a (type, GTK_TYPE_CALENDAR))
+    {
+      /* avoid day 30 and 31, since they don't exist in February */
+      instance = g_object_new (type,
+                               "year", 1984,
+                               "month", 10,
+                               "day", 05,
+                               NULL);
+    }
   /* special casing for singletons */
   else if (g_type_is_a (type, GTK_TYPE_NEVER_TRIGGER))
     instance = (GObject *) g_object_ref (gtk_never_trigger_get ());