Switch away from getSerializable(String) when backwards compatible

[ddohler]

Targeting SDK 33 resulted in a new deprecation warning, that getSerializable(String) in Bundle is now deprecated. However, it appears that the suggested replacement is only available in Android 33+, so this would break compatibility with older devices. Since this is a brand new deprecation in SDK 33, we probably have at least a couple years 🤞 before it actually gets removed, and there may be efforts to provide better backwards compatibility for it, so the best thing to do is probably to wait a bit and see if at some later point we can switch in a backwards-compatible way.