Use symfony/http-client instead of guzzlehttp/guzzle

[andreheeke]

Since Contao 4.9, the third-party dependency "guzzle" is not used anymore. The symfony framework offers a native component named "http-client".

[bezin]

Hello Andre,

thanks for the heads-up. Since it is not an issue that limits the usage of this extension we won't make any changes (now). However, if we continue development of this extension we may change the implementation to remove this dependency.

Cheers