test: prove current Node live-mutex dev with nine clients - #13

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@40f1582b2485089dde7abd97c1529aa768e1baff, actions/setup-java@cf277c60eb25467037889841efdb72551f06f6c3. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

setup-java v4 is deprecated and will no longer receive updates. Please migrate to actions/setup-java@v5.