Guzzle não Instala

Carlos, bom dia. 

Eu coloquei a linha de instalação no require do composer.json e rodei o composer update mas não instalou o guzzle. Uso laravel 5.5 

...
Discovered Package: tymon/jwt-auth
Package manifest generated successfully.
root@6effc797ca78:/var/www/helper# 

Meu composer:
        "php": ">=7.1.0",
        "barryvdh/laravel-dompdf": "^0.8.3",
        "fideloper/proxy": "~3.3",
        "jeroennoten/laravel-adminlte": "^1.24",
        "laravel/framework": "5.5.*",
        "laravel/tinker": "~1.0",
        "laravelcollective/html": "^5.4.0",
        "maatwebsite/excel": "^3.1",
        "tymon/jwt-auth": "dev-develop",
        "guzzlehttp/guzzle": "~6.0"