Adopt a versioning scheme like llvm-sys

[edg-l]

llvm-sys uses versions like llvm170-0, llvm180-0 etc which allow to differentiate between different llvm versions, the minor upgrade from 0.2.1 to 0.2.2 is a big breaking change against semver due to llvm versions going from 17 to 18 (i know under 0.x the rules arent the same but i think its not bad to be a bit dev friendly)