What are the new features in MvvmCross 9.3.1

1. Navigation for Result from ViewModel: This version includes a contribution by @entdark that adds back the functionality for waiting for a result from a ViewModel during navigation. This feature was previously removed in MvvmCross 8 but has been reintroduced with new methods in `MvxNavigationService`, along with new types like `IMvxResultViewModelManager`, `MvxResultAwaitingViewModel`, and `MvxResultSettingViewModel`. Detailed documentation on how to use this feature can be found on the MvvmCross website, and there is a sample in the Playground project for reference[1].

2. Migration to xUnit v3: The tests in MvvmCross have been migrated to xUnit v3 by @Cheesebaron. This update ensures that the testing framework is modern and efficient, aligning with current best practices in .NET development[1].

3. Allow Null Values in Text Bindings: A bug fix by @Cheesebaron allows null values to be bound to Text in UILabel Text Target Binding. This change enhances flexibility in handling data binding scenarios where null values are expected or encountered[1].

4. Other Improvements: While not new features per se, MvvmCross 9.3.1 also includes various other improvements and bug fixes, such as updates to the build process and documentation, ensuring a more stable and efficient development experience.

These updates reflect the ongoing effort to enhance MvvmCross's capabilities and compatibility with evolving .NET ecosystems, particularly in cross-platform app development.