The requested package guzzlehttp/guzzle ^7.3 exists as guzzlehttp/guzzle code example
Example: composer require guzzlehttp/guzzle
To install guzzlehttp
composer require guzzlehttp/guzzle
Ref : https://packagist.org/packages/guzzlehttp/guzzle
To install guzzlehttp
composer require guzzlehttp/guzzle
Ref : https://packagist.org/packages/guzzlehttp/guzzle