fix(stackable-versioned): Handle fields added in later versions

[Techassi]

Found by @sbernauer

#[versioned(  version(name = "v1alpha1"),  version(name = "v1alpha2"),  version(name = "v1beta1"),  version(name = "v1") )] struct Foo { username: String, #[versioned(added(since = "v1alpha2"))] first_name: String, #[versioned(added(since = "v1beta1"))] last_name: String, }