Use degrees of freedom in simple ranktest and bump to 0.8.4 - #30

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/cache@v4, actions/checkout@v4, actions/github-script@60a0d83039c74a4aee543508d2ffcb1c3799cdea, julia-actions/setup-julia@v2. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Consider using `julia-actions/cache` to speed up runs https://github.com/julia-actions/cache To ignore, set input `ignore-no-cache: true`