fix warnings

lib/something_erlang/accounts/user.ex

@@ -8,7 +8,7 @@ defmodule SomethingErlang.Accounts.User do
     timestamps()
   end
 
-  def registration_changeset(user, attrs, opts \\ []) do
+  def registration_changeset(user, attrs, _opts \\ []) do
     user
     |> cast(attrs, [:bbuserid])
     |> validate_required([:bbuserid])