Laravel 5.6 -> Não funciona!

[marcellopato]

Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - Conclusion: don't install jansenfelipe/cep-gratis v4.0.2
    - Conclusion: don't install jansenfelipe/cep-gratis v4.0.1
    - Conclusion: don't install jansenfelipe/cep-gratis v4.0.0
    - Conclusion: remove symfony/css-selector v4.1.0
    - Installation request for jansenfelipe/cep-gratis ^4.0 -> satisfiable by jansenfelipe/cep-gratis[4.0.x-dev, v4.0.0, v4.0.1, v4.0.2].
    - Conclusion: don't install symfony/css-selector v4.1.0
    - jansenfelipe/cep-gratis 4.0.x-dev requires symfony/css-selector ^3.2 -> satisfiable by symfony/css-selector[3.2.x-dev, 3.3.x-dev, 3.4.x-dev, v3.2.0, v3.2.0-BETA1, v3.2.0-RC1, v3.2.0-RC2, v3.2.1, v3.2.10, v3.2.11, v3.2.12, v3.2.13, v3.2.14, v3.2.2, v3.2.3, v3.2.4, v3.2.5, v3.2.6, v3.2.7, v3.2.8, v3.2.9, v3.3.0, v3.3.0-BETA1, v3.3.0-RC1, v3.3.1, v3.3.10, v3.3.11, v3.3.12, v3.3.13, v3.3.14, v3.3.15, v3.3.16, v3.3.17, v3.3.2, v3.3.3, v3.3.4, v3.3.5, v3.3.6, v3.3.7, v3.3.8, v3.3.9, v3.4.0, v3.4.0-BETA1, v3.4.0-BETA2, v3.4.0-BETA3, v3.4.0-BETA4, v3.4.0-RC1, v3.4.0-RC2, v3.4.1, v3.4.10, v3.4.11, v3.4.2, v3.4.3, v3.4.4, v3.4.5, v3.4.6, v3.4.7, v3.4.8, v3.4.9].

[ricatom]

Não sei se conseguiu resolver, mas...

Eu tive o mesmo erro e consegui instalar colocando "jansenfelipe/cep-gratis": "^4.0" no composer.json e depois executando composer update

[marcellopato]

@ricardotomim
Consegui instalar e a app continua funcionando, mas ainda não testei se a livraria está resgatando o CNPJ. Você testou?