Add all required target frameworks

Author: mauroservienti

.github/workflows/ci.yml

@@ -31,7 +31,9 @@ jobs:
       - name: Setup .NET SDK
         uses: actions/[email protected]
         with:
-          dotnet-version: 6.0.x
+          dotnet-version: |
+            6.0.x
+            7.0.x
       - name: Build
         run: dotnet build src --configuration Release
       - name: Tests