Update timestamp when accepting invite, sort by that

Bot/InviteTracker.fs

@@ -86,7 +86,7 @@ let private markInvitedAccepted did =
     connStr
     |> Sql.connect
     |> Sql.parameters [ "did" , Sql.string (string did) ]
-    |> Sql.query "UPDATE invited_user SET accepted = true WHERE discord_id = @did"
+    |> Sql.query "UPDATE invited_user SET accepted = true, updated_at = timezone('utc'::text, now()) WHERE discord_id = @did"
     |> Sql.executeNonQueryAsync
     |> Async.AwaitTask
 
@@ -162,7 +162,7 @@ let private getInvitedUsers userId =
             WITH invite AS (SELECT id FROM invite WHERE inviter = @did)
             SELECT discord_id FROM invited_user, invite
             WHERE invite.id = invited_user.invite_id AND invited_user.accepted = true
-            ORDER BY created_at DESC LIMIT 10
+            ORDER BY updated_at DESC LIMIT 10
         """
     |> Sql.executeAsync (fun read -> read.string "discord_id" |> uint64)
     |> Async.AwaitTask