Target net10.0 in Tests.csproj

Update src/Tests/Tests.csproj to replace the net9 TFM with net10.0 so the test project targets .NET Framework 4.8 and .NET 10.0. This aligns the project with the current .NET runtime naming.

Author: SimonCropp

src/Tests/Tests.csproj

@@ -1,7 +1,7 @@
 
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net48;net9</TargetFrameworks>
+    <TargetFrameworks>net48;net10.0</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="MarkdownSnippets.MsBuild" PrivateAssets="all" />