Install net8 in action

Author: stefannikolei

.github/workflows/build-and-test.yml

@@ -55,7 +55,7 @@ jobs:
         uses: actions/setup-dotnet@v3
         with:
           dotnet-version: |
-            6.0.x
+            8.0.x
 
       - name: DotNet Build
         shell: pwsh