Avoid caching `~/.julia/artifacts/Overrides.toml`

[omus]

If a CI job were to create this file this override file would automatically get cached. We should avoid caching this file as future CI runs may no longer require it which then requires the workflow to be updated to manually delete this file. We should be able to easily exclude this file from the cached files via: https://github.com/actions/toolkit/tree/main/packages/glob#exclude-patterns