Use macos-latest to release ios artifacts in GitHub Actions

[takahirom]

Hello dropbox/differ team,

I noticed that iOS artifacts are not being released due to the use of ubuntu-latest in GitHub Actions. To address this, I propose switching to macos-latest for builds targeting iOS, which should enable the automated release of iOS-compatible binaries.

I've implemented this change in the pull request. Integrating it would significantly benefit iOS developers using Kotlin Multiplatform.

Thank you for considering this update.

https://central.sonatype.com/search?q=com.dropbox.differ

[CLAassistant]

All committers have signed the CLA.

[takahirom]

@rharter
Thanks for merging this.
I found something related to this issue. If we use a Mac, we can release the iOS artifact, but we can't release the Linux artifact. We might need to use separate tasks and operating systems, similar to the KMP library template. Here's the reference: https://github.com/Kotlin/multiplatform-library-template/blob/main/.github/workflows/deploy.yml.

Although publishing on separate operating systems is ideal, I think this PR is better than just using Linux because iOS is a major use case for KMP.

By the way, Roborazzi is using differ, and we want to use the iOS artifact. If you're okay with the above comment, could you provide a release?