upgrade dotnet version in github wf

Author: BalintBende

.github/workflows/main.yml

@@ -13,7 +13,7 @@ jobs:
 
       - uses: actions/setup-dotnet@v4
         with:
-          dotnet-version: '8.0.x'
+          dotnet-version: '9.0.x'
 
       - name: Install dotnet format
         run: dotnet tool update --global dotnet-format