chore: Adjust uwp build

Author: jeromelaban

src/TestApp/uwp/Uno.UI.RuntimeTests.Engine.UWP/Uno.UI.RuntimeTests.Engine.Uwp.csproj

@@ -20,6 +20,8 @@
   <PropertyGroup>
     <!-- Workaround for https://github.com/unoplatform/uno/discussions/5007, to remove when original VS issue is fixed. -->
     <SynthesizeLinkMetadata>true</SynthesizeLinkMetadata>
+    <!-- System.Private.Uri is transitively updated by the runtime -->
+    <NoWarn>$(NoWarn);NU1903</NoWarn>
   </PropertyGroup>
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>