Font Assets dont work in Windows Server 2019

### Describe the bug

I upgraded from .net6 to .net 8 and from WindowsAppSdk 1.5 to 1.6.

I have a fontfamily that I added to a ResourceDirectory

```

/Assets/Fonts/Font Awesome 6 Free-Solid-900.otf#Font Awesome 6 Free Solid

```

And I use it like this

```

```

This worked fine before I updated and it still does on my Win11 Machine.

But on my Windows Server 2019 (17763.1697) Machine it looks like this:


### Steps to reproduce the bug

1: Add a custom Font to a WinUi3 Project
2: Use it on a Button
3: Run the App on a Windows Server 2019 Machine

### Expected behavior

The Button should use the font icon

### Screenshots

_No response_

### NuGet package version

WinUI 3 - Windows App SDK 1.6.1: 1.6.240923002

### Windows version

Windows 10 (1809): Build 17763

### Additional context

_No response_

Reproduce the reported FontFamily and FontIcon setup in a WinUI 3 project on Windows Server 2019 build 17763, comparing it with Windows 11. No source files or tests are named; investigate the ResourceDictionary font asset and FontIcon entry point using Windows App SDK 1.6.1. Done means the custom Font Awesome icon renders on the Server 2019 button as expected.

Written by the indexing model from the issue text.