[spec] exclude .NET Framework tests on Ubuntu

Author: i4004

.github/workflows/build.yml

@@ -13,6 +13,9 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, windows-latest]
+        include:
+          - os: ubuntu-latest
+            test-framework-command: --framework net8.0
 
     steps:
       - name: Code Checkout
@@ -30,7 +33,7 @@ jobs:
         run: dotnet build --no-restore -c Release
 
       - name: Perform Unit Testing
-        run: dotnet test --no-build -c Release --verbosity normal --filter "TestCategory!=Benchmark"
+        run: dotnet test --no-build -c Release ${{ matrix.test-framework-command }} --verbosity normal --filter "TestCategory!=Benchmark"
 
       - name: Create Package
         run: dotnet pack Simplify.Web/Simplify.Web.csproj --no-build -c Release -o ./publish