Update dotnetcore.yml

Author: usercode

Diff for: .github/workflows/dotnetcore.yml

@@ -15,7 +15,7 @@ jobs:
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 6.0.x
+        dotnet-version: 9.0.x
     - name: Build with dotnet
       run: dotnet build --configuration Release "./src/AsyncKeyLock.sln"
     - name: Run unit tests