Install Error at Composre about some package missed

[bestony]

error

☁  TranslatePlatform [master] ⚡ composer require graham-campbell/github
Using version ^5.1 for graham-campbell/github
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - knplabs/github-api 2.0.1 requires php-http/client-implementation ^1.0 -> no matching package found.
    - knplabs/github-api 2.0.0 requires php-http/client-implementation ^1.0 -> no matching package found.
    - graham-campbell/github v5.1.0 requires knplabs/github-api ^2.0 -> satisfiable by knplabs/github-api[2.0.0, 2.0.1].
    - Installation request for graham-campbell/github ^5.1 -> satisfiable by graham-campbell/github[v5.1.0].

Potential causes:
 - A typo in the package name
 - The package is not available in a stable-enough version according to your minimum-stability setting
   see <https://getcomposer.org/doc/04-schema.md#minimum-stability> for more details.

Read <https://getcomposer.org/doc/articles/troubleshooting.md> for further common problems.

Installation failed, reverting ./composer.json to its original content.

mac php7.0.15

[GrahamCampbell]

Please see the installation documentation on the readme:

https://github.com/GrahamCampbell/Laravel-GitHub#installation.

[GrahamCampbell]

You are missing an "implementation" of a "virtual package".

[bestony]

Well.For Others .
First i install "php-http/guzzle6-adapter": "^1.1",,then i install "graham-campbell/github": "^5.0".
step by step and not common install