Fix ios build on old xcode

[juliesaia-vendora]

Version >=0.5.0 was failing to build on XCode 15.2:

func introspectTabView(closure: @escaping (UITabBarController) -> Void) -> some View {
  44 |     self
> 45 |       .introspect(
     |        ^ call to main actor-isolated instance method 'introspect' in a synchronous nonisolated context

I think it's related to a recent change to @mainactor in XCode 16?

Whatever the case, the package is building for me with this change 🙌

[okwasniewski]

Thanks!