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

  Problem 1
    - Installation request for ezsystems/recommendation-bundle ~1.0.0 -> satisfiable by ezsystems/recommendation-bundle[v1.0.0].
    - Conclusion: remove guzzlehttp/guzzle 6.2.0
    - ezsystems/recommendation-bundle v1.0.0 requires guzzlehttp/guzzle ~5.0 -> satisfiable by guzzlehttp/guzzle[5.0.0, 5.0.1, 5.0.2, 5.0.3, 5.1.0, 5.2.0, 5.3.0].
    - Can only install one of: guzzlehttp/guzzle[6.2.0, 5.0.0].
    - Can only install one of: guzzlehttp/guzzle[6.2.0, 5.0.1].
    - Can only install one of: guzzlehttp/guzzle[6.2.0, 5.0.2].
    - Can only install one of: guzzlehttp/guzzle[6.2.0, 5.0.3].
    - Can only install one of: guzzlehttp/guzzle[6.2.0, 5.1.0].
    - Can only install one of: guzzlehttp/guzzle[6.2.0, 5.2.0].
    - Can only install one of: guzzlehttp/guzzle[6.2.0, 5.3.0].
    - Installation request for guzzlehttp/guzzle (locked at 6.2.0) -> satisfiable by guzzlehttp/guzzle[6.2.0].

leo:ezpublish-5.4 tretas$ composer show | grep guzz
guzzle/guzzle                                v3.9.3             PHP HTTP client. This library is deprecated in favor of https://packagist.org/packages/guzz...
guzzlehttp/guzzle                            6.2.0              Guzzle is a PHP HTTP client library
guzzlehttp/promises                          1.2.0              Guzzle promises library
guzzlehttp/psr7                              1.3.0              PSR-7 message implementation