Remove the caching config on the build job

[mgax]

The publish pipeline failed with the following error:

Error: Cache folder path is retrieved for pip but doesn't exist on disk: /home/runner/.cache/pip. This likely indicates that there are no dependencies to cache. Consider removing the cache step if it is not needed.

The cache is likely empty because we're using hynek/setup-cached-uv@v2 to install packages, which does its own caching, so I've removed the offending cache step.