Packages that use tarballs as the primary download method cannot
change from gzip to zstd without upstream providing that zstd.
For packages that use https://github.com/*/*/archive/ directly,
without dl_github_archive, only .tar.gz or .zip can be used.
This reverts part of 454dda3433 (treewide: change to zstd tarballs,
2025-12-15) for packages umoci, ndt, skopeo.
Fixes: 454dda3433 ("treewide: change to zstd tarballs")
Change to zstd compressed instead of gz-compressed tarballs. zstd
compresses 7-8 times faster and decompresses 2-3 times faster.
This change also make sharing tarballs between different branches
possible, because OpenWrt 25.12 uses zstd as default.
Signed-off-by: Andreas Gnau <andreas.gnau@iopsys.eu>
