GitHub Action Nuget restore configuration

nuget-github-config.yml

# This gist demonstrated how you can configure NuGet source without storing the credentials in plaintext on the disc
# We enable this by only storing references to environment variables into the NuGet configuration (%NUGET_USERNAME%)

name: Configure NuGet source on private GitHub package repository
jobs:
  build:
    env:
      NUGET_USERNAME: ${{ secrets.NUGET_USERNAME }} #Needs to be the user associated with the personal access token (PAT)
      NUGET_PATTOKEN: ${{ secrets.NUGET_PATTOKEN }} #PAT only needs the read:packages scope
      NUGET_GITHUB_ORGANISATION: ${{ github.repository_owner }} #Name of the organization where the feed is stored
    steps:
    - run: |
        if ! grep -q "github_$NUGET_GITHUB_ORGANISATION" ~/.nuget/NuGet/NuGet.Config; 
        then 
          dotnet nuget add source --username "%NUGET_USERNAME%" --password "%NUGET_PATTOKEN%" \
            --store-password-in-clear-text --name "github_$NUGET_GITHUB_ORGANISATION" \
            "https://nuget.pkg.github.com/$NUGET_GITHUB_ORGANISATION/index.json"; 
        fi