fix listeners / detaching listeners for firebase in ios app

[colinlemmehelp]

https://github.com/peterfriese/BookSpine/blob/main/code/BookSpine/ViewModels/BooksViewModel.swift Need to use .subscribe() and .unsubscribe() to handle these

[colinlemmehelp]

https://stackoverflow.com/questions/55819951/firebase-realtime-listener-concept-how-to-detach-unsubscribe-from-the-listen

try this? basically just call the value that is created there.. I think

[colinlemmehelp]

Or try this: https://stackoverflow.com/questions/61822307/how-to-remove-observer-in-swiftui

[colinlemmehelp]

[colinlemmehelp]

https://stackoverflow.com/questions/46756915/how-to-detach-firestore-listener

https://firebase.google.com/docs/firestore/query-data/listen