⬇️ downgrade System.Text.Encoding.CodePages to 9.0.8 in test project

Author: techouse

QsNet.Tests/QsNet.Tests.csproj

@@ -8,10 +8,7 @@
         <PackageReference Include="FluentAssertions" Version="8.6.0"/>
         <PackageReference Include="JetBrains.Annotations" Version="2025.2.0"/>
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.14.1"/>
-        <PackageReference
-                Include="System.Text.Encoding.CodePages"
-                Version="10.0.0-preview.6.25358.103"
-        />
+        <PackageReference Include="System.Text.Encoding.CodePages" Version="9.0.8"/>
         <PackageReference Include="xunit" Version="2.9.3"/>
         <PackageReference Include="xunit.runner.visualstudio" Version="3.1.4">
             <PrivateAssets>all</PrivateAssets>