Request: Add support for new runner label `ubuntu-slim`

[ryo246912]

Summary

It seems a new runner label, ubuntu-slim, is now available in GitHub Actions.
Could you please consider adding default support for this label in actionlint?

Current Behavior

With the current version of actionlint, using runs-on: ubuntu-slim results in the following [runner-label] error.

.github/workflows/actionlint.yml:16:14: label "ubuntu-slim" is unknown. available labels are "windows-latest", "windows-latest-8-cores", "windows-2025", "windows-2022", "windows-11-arm", "ubuntu-latest", "ubuntu-latest-4-cores", "ubuntu-latest-8-cores", "ubuntu-latest-16-cores", "ubuntu-24.04", "ubuntu-24.04-arm", "ubuntu-22.04", "ubuntu-22.04-arm", "macos-latest", "macos-latest-xl", "macos-latest-xlarge", "macos-latest-large", "macos-26-xlarge", "macos-26", "macos-15-intel", "macos-15-xlarge", "macos-15-large", "macos-15", "macos-14-xl", "macos-14-xlarge", "macos-14-large", "macos-14", "macos-13-xl", "macos-13-xlarge", "macos-13-large", "macos-13", "self-hosted", "x64", "arm", "arm64", "linux", "macos", "windows". if it is a custom label for self-hosted runner, set list of labels in actionlint.yaml config file [runner-label]
   |
16 |     runs-on: ubuntu-slim
   |              ^~~~~~~~~~~

Expected Behavior

I expect actionlint not to raise an error when runs-on: ubuntu-slim is specified in a workflow file.

Workaround

I am aware that I can work around this error by adding ubuntu-slim to the self-hosted-runner-labels in my .actionlint.yml file.
However, if ubuntu-slim is an officially supported or widely used label, I believe it would be beneficial for it to be supported by default in actionlint.

[ryo246912]

It seems a PR has already been created for #585.

[yu-iskw]

@rhysd I appreciate if you could release a new version for ubuntu-slim.