Fixing ci dotnet version

Author: gigi81

.github/workflows/ci.yml

@@ -23,10 +23,8 @@ jobs:
         uses: actions/setup-dotnet@v4
         with:
           dotnet-version: | 
-            5.0.x
-            6.0.x
-            7.0.x
             8.0.x
+            9.0.x
       - name: Run tests
         run: dotnet test --collect:"XPlat Code Coverage"  --logger "GitHubActions"
       - name: Upload coverage