Allow per-repo publish agent OS var, and non-nuget.org prereleases

Prereleases will be used to test via the CI feed exclusively. Once verified, publishing the release will push to nuget.org.

This makes it easier to test before shipping to users.

.github/workflows/publish.yml

@@ -18,7 +18,7 @@ env:
 
 jobs:
   publish:
-    runs-on: ubuntu-latest
+    runs-on: ${{ vars.PUBLISH_AGENT || 'ubuntu-latest' }}
     steps:
       - name: 🤘 checkout
         uses: actions/checkout@v4
@@ -44,13 +44,13 @@ jobs:
       - name: 🚀 nuget
         env:
           NUGET_API_KEY: ${{ secrets.NUGET_API_KEY }}
-        if: env.NUGET_API_KEY != ''
-        run: dotnet nuget push ./bin/**/*.nupkg -s https://api.nuget.org/v3/index.json -k ${{secrets.NUGET_API_KEY}} --skip-duplicate
+        if: ${{ env.NUGET_API_KEY != '' && github.event.action != 'prereleased' }}
+        run: dotnet nuget push ./bin/*.nupkg -s https://api.nuget.org/v3/index.json -k ${{secrets.NUGET_API_KEY}} --skip-duplicate
 
       - name: 🚀 sleet
         env:
           SLEET_CONNECTION: ${{ secrets.SLEET_CONNECTION }}
         if: env.SLEET_CONNECTION != ''
         run: |
           dotnet tool install -g --version 4.0.18 sleet 
-          sleet push bin --config none -f --verbose -p "SLEET_FEED_CONTAINER=nuget" -p "SLEET_FEED_CONNECTIONSTRING=${{ secrets.SLEET_CONNECTION }}" -p "SLEET_FEED_TYPE=azure" || echo "No packages found"
+          sleet push bin --config none -f --verbose -p "SLEET_FEED_CONTAINER=nuget" -p "SLEET_FEED_CONNECTIONSTRING=${{ secrets.SLEET_CONNECTION }}" -p "SLEET_FEED_TYPE=azure" || echo "No packages found"