Update main.yml

Author: oivindhagen

.github/workflows/main.yml

@@ -26,7 +26,7 @@ jobs:
     - name: Setup .NET
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 6.0.x
+        dotnet-version: 9.0.x
 
     - name: Build
       run: dotnet pack $SOLUTION --configuration $BUILD_CONFIG /p:Version=$BUILD_VERSION