Fix update feeds thinking all items already exist

Repo.exists? needs a query, not the keyword list

lib/frenzy/item.ex

@@ -1,6 +1,7 @@
 defmodule Frenzy.Item do
   use Ecto.Schema
   import Ecto.Changeset
+  import Ecto.Query
   alias FrenzyWeb.Router.Helpers, as: Routes
   alias FrenzyWeb.Endpoint
 
@@ -87,6 +88,6 @@ defmodule Frenzy.Item do
   end
 
   def exists?(feed_id, guid) do
-    Frenzy.Repo.exists?(__MODULE__, feed_id: feed_id, guid: guid)
+    Frenzy.Repo.exists?(from i in __MODULE__, where: i.feed_id == ^feed_id and i.guid == ^guid)
   end
 end

lib/frenzy/update_feeds.ex

@@ -159,7 +159,6 @@ defmodule Frenzy.UpdateFeeds do
     end
 
     Enum.each(rss.items, fn entry ->
-      # todo: use Repo.exists for this
       unless Item.exists?(feed.id, entry.guid) do
         CreateItem.start_link(feed, entry)
       end