Update Unsplash Library for PHP 8.1 Compliance

The Unsplash PHP library is currently not written to PHP 8 standards, so with the current version of this module, saving an Unsplash Media entity triggers a hefty amount of deprecation warnings. See this issue. I tested this locally by changing the module to a custom module, and then downloading the suggested Unsplash version from the link supplied, and all seemed well. Unfortunately just applying this patch won't work, as the library is downloaded before the patch is installed, so I'm not sure how to "test" this. Thoughts?