Update dotnetcore.yml

.github/workflows/dotnetcore.yml

@@ -16,6 +16,6 @@ jobs:
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 4.7 
+        dotnet-version: 3.1 
     - name: Build with dotnet
       run: dotnet build --configuration Release