Tests: update to run on .NET 8

The new MSBuild package doesn't support execution under .NET 6 anymore.

Author: ForNeVeR

.github/workflows/main.yml

@@ -26,10 +26,12 @@ jobs:
       - name: Fetch the sources
         uses: actions/checkout@v4
 
-      - name: Set up .NET 6.0 SDK
+      - name: Set up .NET SDK
         uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: '6.0.x'
+          dotnet-version: |
+            6.0.x
+            8.0.x
 
       - name: Build NuGet packages
         shell: pwsh

PascalABC.NET.SDK.UnitTests/PascalABC.NET.SDK.UnitTests.csproj

@@ -1,7 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
     <PropertyGroup>
-        <TargetFramework>net6.0</TargetFramework>
+        <TargetFramework>net8.0</TargetFramework>
         <ImplicitUsings>enable</ImplicitUsings>
         <Nullable>enable</Nullable>