Use net8.0 for scenarios libraries (dotnet#4342)

Author: caaavik-msft

.vscode/settings.json

@@ -8,7 +8,7 @@
         "**/logs/": true,
         "**/obj/": true,
         "**/packages/": true,
-        "tools/": true,
+        "/tools/": true,
     },
     "python.analysis.typeCheckingMode": "strict",
     "python.analysis.diagnosticSeverityOverrides": {

src/tools/ScenarioMeasurement/Directory.Build.props

@@ -3,7 +3,7 @@
     <Import Project="Sdk.props" Sdk="Microsoft.DotNet.Arcade.Sdk" />
     <PropertyGroup>
         <FallbackTargetFramework>net8.0</FallbackTargetFramework>
-        <LibrariesTargetFramework>net6.0</LibrariesTargetFramework>
+        <LibrariesTargetFramework>net8.0</LibrariesTargetFramework>
         <NoWarn>$(NoWarn);CS8002</NoWarn>
         <LangVersion>latest</LangVersion>
     </PropertyGroup>