According to upstream, lz4 is ABI and ABI backwards compatible, so we should be able to do this without having to rebuild downward dependencies if we're careful.
Scratch build: https://cbs.centos.org/koji/taskinfo?taskID=2592600
Testing went well, built and tagged lz4-1.9.3-3.hs.el8 for -release.
Metadata Update from @dcavalca: - Issue status updated to: Closed (was: Open)