Create a release with guzzlehttp/guzzle ^7.0

For PHP8 compatiblity guzzle 7 is required. As stated [in the release notes](https://github.com/udger/udger-php/releases/tag/v3.1.4), guzzle 7 is supported, but this change did not make it into the latest release 3.1.4. The ^7.0 constraint is in master only.