错误：当前运行程序（ubuntu-24.04-x64）被检测为自托管，因为该平台与GitHub托管的运行程序映像不匹配（或者该映像已弃用且不再受支持）。

Error: The current runner (ubuntu-24.04-x64) was detected as self-hosted because the platform does not match a GitHub-hosted runner image (or that image is deprecated and no longer supported).
In such a case, you should install Ruby in the $RUNNER_TOOL_CACHE yourself, for example using https://github.com/rbenv/ruby-build
You can take inspiration from this workflow for more details: https://github.com/ruby/ruby-builder/blob/master/.github/workflows/build.yml
$ ruby-build 3.1.4 /opt/hostedtoolcache/Ruby/3.1.4/x64
Once that completes successfully, mark it as complete with:
$ touch /opt/hostedtoolcache/Ruby/3.1.4/x64.complete
It is your responsibility to ensure installing Ruby like that is not done in parallel.