Enable all target frameworks in build validation

.github/workflows/build.yml

@@ -52,6 +52,10 @@ jobs:
       - name: Add msbuild to PATH
         uses: microsoft/setup-msbuild@v1.0.3
 
+      - name: Enable all TargetFrameworks
+        working-directory: ./common/Scripts/
+        run: ./UseTargetFrameworks.ps1 all
+
       - name: MSBuild
        # working-directory: ./
         run: msbuild.exe Toolkit.Labs.All.sln /restore -p:Configuration=Release