Eleventy Image v2.0.0

The only breaking change here is that we now use Eleventy Fetch v3.0.0 internally instead of @11ty/eleventy-cache-assets. https://github.com/11ty/eleventy-fetch/releases/tag/v3.0.0

The algorithm to generate file names used for cache has changed: previously saved .cache folders generated by eleventy-cache-assets v2 will not be carried forward and new remote requests will be made!

While this might not technically be classified as a breaking change (new cache files and new remote resource requests), we wanted to play it extra safe here. No other breaking changes included.