Add Activity Pub endpoints cache

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/service/feed.ex

@@ -72,11 +72,10 @@ defmodule Mobilizon.Service.Feed do
   defp get_entry(%Event{} = event) do
     with {:ok, html, []} <- Earmark.as_html(event.description) do
       entry =
-        Entry.new(event.url, event.inserted_at, event.title)
+        Entry.new(event.url, event.publish_at || event.inserted_at, event.title)
         |> Entry.link(event.url, rel: "alternate", type: "text/html")
         |> Entry.content({:cdata, html}, type: "html")
-
-      entry = if event.publish_at, do: Entry.published(entry, event.publish_at), else: entry
+        |> Entry.published(event.publish_at || event.inserted_at)
 
       # Add tags
       entry =