title: How to validate no duplications with Yup
body: <p>I have a validation that only validates its fields by checking if they are break its only rules, but it allows duplications inside the Array.</p>
  
  <p>I want some sort of condition that won't allow duplicated values inside of it.</p>
  
  <p>My object:</p>
  
  <pre><code>respostas: Yup.array()
      .of(
        Yup.object().shape({
          nome: Yup.string()
            .trim()
            .max(1000, Messages.RESPOSTA_ENQUETE_TAMANHO_MAXIMO)
            .required(Messages.CAMPO_OBRIGATORIO)
        })
      )
      .required(Messages.RESPOSTA_QUANTIDADE_MINIMA)
  </code></pre>
  
  <p>For example, I would have an array like this: [aaa,bbb,aaa] allowed, but I don't want this duplication.</p>