Update actions/download-artifact action to v6

Author: renovate[bot]

.github/workflows/publish-nuget.yml

@@ -49,7 +49,7 @@ jobs:
         run: |
           echo "$GITHUB_CONTEXT"
       - name: 🚀 NuGet
-        uses: actions/download-artifact@v4
+        uses: actions/download-artifact@v6
         with:
           github-token: '${{ secrets.GITHUB_TOKEN }}'
           name: 'nuget'