fix(security): resolve cargo audit advisories + bump crux to 0.19 - #124

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v2, CondeNast/conventional-pull-request-action@v0.2.0. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/