Update actions/upload-artifact action to v6

Author: dependencyupdates[bot]

.github/workflows/ci.yml

@@ -45,7 +45,7 @@ jobs:
         run: dotnet build src --configuration Release
       - name: Upload packages
         if: matrix.name == 'Windows'
-        uses: actions/upload-artifact@v5.0.0
+        uses: actions/upload-artifact@v6.0.0
         with:
           name: NuGet packages
           path: nugets/

.github/workflows/release.yml

@@ -31,7 +31,7 @@ jobs:
           client-secret: ${{ secrets.AZURE_KEY_VAULT_CLIENT_SECRET }}
           certificate-name: ${{ secrets.AZURE_KEY_VAULT_CERTIFICATE_NAME }}
       - name: Publish artifacts
-        uses: actions/upload-artifact@v5.0.0
+        uses: actions/upload-artifact@v6.0.0
         with:
           name: nugets
           path: nugets/*