Update dependence guzzlehttp/guzzle to 7.0 version

[andreau2d]

Problem 1
- jayzeng/virustotalapi 0.1.9 requires guzzlehttp/guzzle ^6.2.0 -> satisfiable by guzzlehttp/guzzle[6.2.0, 6.2.1, 6.2.2, 6.2.3, 6.3.0, 6.3.1, 6.3.2, 6.3.3, 6.4.0, 6.4.1, 6.5.0, 6.5.1, 6.5.2, 6.5.3, 6.5.4, 6.5.5, 6.5.x-dev] but these conflict with your requirements or minimum-stability.

- Installation request for jayzeng/virustotalapi ^0.1.9 -> satisfiable by jayzeng/virustotalapi[0.1.9].

[jayzeng]

thanks for reporting. I will resolve it soon.