$ luarocks --local install lume
Error: No results matching query were found for Lua 5.4.
To check if it is available for other Lua versions, use --check-lua-versions.
It looks like it just needs to be published to luarocks for 5.4; for what it's worth, I just tried cloning the repo and running the tests in 5.4 and they all passed without issue.
Will not install for Lua 5.4: