chore: Use Xcode 26.1 and iOS 26.1 on CI

[github-actions]

Note

The pull request "chore: Use Xcode 26.1 and iOS 26.1 on CI" was created by @itaybre but did not reference an issue. Therefore this issue was created for better visibility in external tools like Linear.

Test Xcode 26.1 and iOS 26.1 beta for CI

Given how unstable iOS 26.0 has been recently, let's try using iOS 26.1 beta

#skip-changelog

[linear]

COCOA-815