Update Roc and Roc dependencies versions in tests-runner

[rrramiro]

This PR updates the versions of Roc and its libraries used in the roc-tests-runner to align with the recently updated exercises in exercism/roc#185.

Changes

Updated Roc version from 0.0.0-apha2-rolling to alpha4-rolling
Updated Roc dependencies to match target versions :

https://github.com/roc-lang/basic-cli/releases/download/0.20.0/X73hGh05nNTkDHU06FHC0YfFaQB1pimX7gncRcao5mU.tar.br
https://github.com/imclerran/roc-isodate/releases/download/v0.6.2/73w_H-aSJNcWqtXvMG4JQw_HoaApMBLnE92XD4OcVGU.tar.br

Motivation
The exercises were recently updated to newer versions of Roc, but the roc-tests-runner was still using older versions. This version mismatch was causing test failures (see message below). By updating the tests-runner dependencies, we ensure compatibility between the runner and the exercises.

We received the following error when we ran your code:
Downloading https://github.com/roc-lang/basic-cli/releases/download/0.20.0/X73hGh05nNTkDHU06FHC0YfFaQB1pimX7gncRcao5mU.tar.br
    into /root/.cache/roc/packages

── HTTP ERROR in /mnt/exercism-iteration/hello-world-test.roc ──────────────────

I tried to download from this URL:

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

But I encountered a network error:

    error sending request for url (https://github.com/roc-lang/basic-cli/releases/download/0.20.0/X73hGh05nNTkDHU06FHC0YfFaQB1pimX7gncRcao5mU.tar.br): error trying to connect: dns error: failed to lookup address information: Temporary failure in name resolution

[github-actions]

Hello. Thanks for opening a PR on Exercism 🙂

We ask that all changes to Exercism are discussed on our Community Forum before being opened on GitHub. To enforce this, we automatically close all PRs that are submitted. That doesn't mean your PR is rejected but that we want the initial discussion about it to happen on our forum where a wide range of key contributors across the Exercism ecosystem can weigh in.

You can use this link to copy this into a new topic on the forum. If we decide the PR is appropriate, we'll reopen it and continue with it, so please don't delete your local branch.

If you're interested in learning more about this auto-responder, please read this blog post.

---

Note: If this PR has been pre-approved, please link back to this PR on the forum thread and a maintainer or staff member will reopen it.

[Anton-4]

Thank you very much @rrramiro! I totally forgot to update the test runner.

[rrramiro]

Thanks @Anton-4 for the review and merge!