execa is used in platform-ios package but is not in package.json as dependency

[DomiR]

Environment

Description

Like other sub-packages from this repo, platform-ios is using execa for easy multi-platform execution. The problem is that if one has a higher version of exec a in the apps devDependencies (e.g. v6 with is esm only) the cli tool will crash.

All we need to do is to add execa as a dependency to platform-ios like all the other packages.