fix: old imports

[AleksandrSl]

These imports seems to be stale after project structure update.
I'm also not sure why the file is read anew everytime and not reused 🤔

To run the benchmarks as stated in the readme I also had to update imports in parser.luau to

local cst = require("lossless/cst")
local span = require("lossless/span")

but I don't think it's a correct solution, Maybe adding init.lua to lossless is a better way 🤔