don't allow reassigning token

lib/cannery/invites/invite.ex

@@ -50,7 +50,7 @@ defmodule Cannery.Invites.Invite do
   @spec update_changeset(t() | new_invite(), attrs :: map()) :: Changeset.t(t() | new_invite())
   def update_changeset(invite, attrs) do
     invite
-    |> cast(attrs, [:name, :token, :uses_left, :disabled_at])
+    |> cast(attrs, [:name, :uses_left, :disabled_at])
     |> validate_required([:name, :token, :user_id])
     |> validate_number(:uses_left, greater_than_or_equal_to: 0)
   end