Keep each worktree's signatures separate - #903

Error: Unavailable version 2.6.10 for ruby on ubuntu-26.04 ruby-2.6.10 is the latest 2.6.x release. Use a newer ruby version on ubuntu-26.04, or an older runner image for ruby 2.6. Note that ubuntu-latest and macos-latest move to newer runner images over time. Cause: Unexpected HTTP response: 404 at /home/runner/work/_actions/ruby/setup-ruby/v1/dist/index.js:45918:15 at process.processTicksAndRejections (node:internal/process/task_queues:104:5) at async body (/home/runner/work/_actions/ruby/setup-ruby/v1/dist/index.js:372:14)

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