Update dotnetcore.yml

Author: justcoding121

.github/workflows/dotnetcore.yml

@@ -17,10 +17,6 @@ jobs:
     runs-on: windows-latest
     steps:
     - uses: actions/checkout@v2
-    - name: Setup .NET Core
-      uses: actions/setup-dotnet@v1
-      with:
-        dotnet-version: '6.0.x'
     - name: Install DocFX
       run: choco install docfx -y
     - name: Build