Register latest Stan versions: v10.8.3 & v10.8.2 to JuliaRegistries

[matthew-liu-1]

Would we be able to register these later versions of Stan.jl the Julia Package Registry please?

Latest here is 10.8.1
https://github.com/JuliaRegistries/General/blob/master/S/Stan/Versions.toml#L314

[bparbhu]

Will do we'll start working on it.