Merge pull request #80 from redth-org/ci/fix-workflow

Add back missing checkout action

Author: Cheesebaron

.github/workflows/release-nuget.yml

@@ -9,6 +9,8 @@ jobs:
     runs-on: windows-latest
 
     steps:
+    - uses: actions/checkout@v1
+
     - name: Setup .NET Core
       uses: actions/setup-dotnet@v1
       with: