Provide nice error message when newest Roc (zig compiler) is used to download platform built with old Roc

[Anton-4]

Currently you just get:

-- DOWNLOAD FAILED -------------------------------

Failed to download from https://github.com/roc-lang/basic-cli/releases/download/0.20.0/X73hGh05nNTkDHU06FHC0YfFaQB1pimX7gncRcao5mU.tar.br

Error: InvalidHash

[Anton-4]

Trying to run the old hello world should probably trigger this issue:

app [main!] { cli: platform "https://github.com/roc-lang/basic-cli/releases/download/0.20.0/X73hGh05nNTkDHU06FHC0YfFaQB1pimX7gncRcao5mU.tar.br" }

import cli.Stdout
import cli.Arg exposing [Arg]

main! : List Arg => Result {} _
main! = |_args|
    Stdout.line!("Hello, World!")