fix(git-submodules): refuse a non-positive stale_after, and never report an unreadable history as neglect - #44

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/setup-go@v5, golangci/golangci-lint-action@v7. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/