This PR is to add support for running on watchOS. Since Xcode 12.5 watchOS has been supported but Nimble doesn't currently compile for watchOS.
A new target has been added to the project, along with explicit support in the Package.swift.
I don't believe anything here is a breaking change.
I have a fork of Quick that also supports watchOS. I'll create a PR for that if this PR gets approved and merged.