Fix event online URL AP attachment

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

test/federation/activity_pub/transmogrifier_test.exs

@@ -70,6 +70,8 @@ defmodule Mobilizon.Federation.ActivityPub.TransmogrifierTest do
         assert event.physical_address.url ==
                  "https://event1.tcit.fr/address/eeecc11d-0030-43e8-a897-6422876372jd"
 
+        assert event.online_address == "https://google.com"
+
         {:ok, %Actor{}} = Actors.get_actor_by_url(object["actor"])
       end
     end

test/fixtures/mobilizon-post-activity.json

@@ -35,7 +35,20 @@
     ],
     "id": "https://test.mobilizon.org/events/39026210-0c69-4238-b3cc-986f33f98ed0/activity",
     "object": {
-        "attachment": [],
+        "attachment": [
+            {
+                "href": "https://something.org",
+                "mediaType": "text/html",
+                "name": "Another link",
+                "type": "Link"
+            },
+            {
+                "href": "https://google.com",
+                "mediaType": "text/html",
+                "name": "Website",
+                "type": "Link"
+            }
+        ],
         "attributedTo": "https://test.mobilizon.org/@Alicia",
         "startTime": "2018-02-12T14:08:20Z",
         "cc": [