Support for Windows Server 2025 (win25) ImageOS

[kianmeng]

Is your feature request related to a problem?

Tried to map a target OS from env. variable 'ImageOS' (got win25), but failed. If you're using a self-hosted runner, you should set 'env': 'ImageOS': ... to one of the following: ['ubuntu22', 'ubuntu24', 'win19', 'win22', 'macos13', 'macos14', 'macos15']

Describe the feature you'd like

Support for win25 as target OS, as windows-latest label:

The windows-latest label will migrate from Windows Server 2022 to Windows Server 2025 beginning September 2, 2025. For more information see actions/runner-images#12677

Describe alternatives you've considered

Instead of using windows-latest label, switched to win22 explicitly for now instead.

Additional context

None.

[lpil]

Yes please! This is causing Gleam builds to fail presently.

Thank you for the win22 tip Kian-Meng!

[essen]

Looks like it's missing from this list: https://github.com/erlef/setup-beam/blob/main/src/setup-beam.js#L646-L654

[lpil]

Thanks for the investigation @essen! I'll ask the Gleamlins if anyone wants to make a PR>

[essen]

I have opened a PR.