Upgrade macos runners to Tahoe `macos-26`

[yungyuc]

Github Actions introduced macos-26-arm64 last year. Most of our contributors are using the latest macos. We should upgrade the runner version.

The workflows use both amr64 and intel. When upgrading, we should also make it clear between macos-26-arm64 or macos-26-intel. The tag macos-26 means arm64 but the name is ambiguous and should be avoided.

[ExplorerRay]

I just read the docs, it didn't mention the workflow label with macos-26-arm64.
I also tried it in my local fork, it will keep waiting for the runner. I think we still need to use the ambiguous tag macos-26 for arm64 one.

[yungyuc]

I just read the docs, it didn't mention the workflow label with macos-26-arm64. I also tried it in my local fork, it will keep waiting for the runner. I think we still need to use the ambiguous tag macos-26 for arm64 one.

Thanks for the clarification. There is a file named macos-26-arm64*: https://github.com/actions/runner-images/blob/main/images/macos/macos-26-arm64-Readme.md . The tag is mentioned in the README.md:53 .

Probably the tag was not enabled in the YAML.

[yungyuc]

Done with PR #732.