Switch from xtarfile to libarchive
The former was used for .zst support. It does it by decompressing the whole tarball into a temporary location. With intel-oneapi-basekit exceeding 16G uncompressed size, we're running out of space on gemini.
Switch to libarchive which should be able to stop after reading .PKGINFO without decompressing and/or reading the rest of the .zst package file.