Вашето запитване
$select = "INSERT INTO registro (nome, usuario, email, senha, cpf, rg)
VALUES (:nome, :usuario, email, :senha, :cpf, :rg)";
След промяна Липсва:в имейл
$select = "INSERT INTO registro (nome, usuario, email, senha, cpf, rg)
VALUES (:nome, :usuario, :email, :senha, :cpf, :rg)";