1.0 Add support for Guzzle 7.8

What's Changed

• Update guzzlehttp/guzzle to 7.8 by @JorisCourtois-fulll in #1

New Contributors

• @JorisCourtois-fulll made their first contribution in #1

Full Changelog: https://github.com/fulll/hapiclient-php-guzzle7/commits/1.0