Update dotnet-core-desktop.yml

Update dotnet-version to 6.0.x

Author: joshkempner

.github/workflows/dotnet-core-desktop.yml

@@ -68,7 +68,7 @@ jobs:
     - name: Install .NET Core
       uses: actions/setup-dotnet@v1
       with:
-        dotnet-version: 5.0.101
+        dotnet-version: 6.0.x
 
     # Add  MSBuild to the PATH: https://github.com/microsoft/setup-msbuild
     - name: Setup MSBuild.exe