Update build.yml

Author: ufcpp

.github/workflows/build.yml

@@ -57,8 +57,6 @@ jobs:
     needs: pack
     runs-on: ubuntu-latest
     steps:
-    - name: Checkout
-      uses: actions/checkout@v2
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v1
       with: