Turn off async Notification fetching

This was causing all sorts of SSL errors. Instead of trying to figure
out what is causing those to come in, make the calls sync instead. It
is still pretty snappy. I'll likely come back and look into this in
the future.

src/notification.cr

@@ -36,10 +36,10 @@ class Notification
   end
 
   def self.fetch_async
-    spawn do
+    # spawn do
       Notification.fetch
-    end
-    Fiber.yield
+    # end
+    # Fiber.yield
   end
 
   def self.mark_read_for_card(card : CardDetail)