chore(deps): update actions/upload-artifact action to v6 (#26)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/export-notebooks.yml

@@ -91,7 +91,7 @@ jobs:
           path: public
 
       - name: 📦 Upload Generated Artifacts
-        uses: actions/upload-artifact@v4
+        uses: actions/upload-artifact@v6
         if: always()
         with:
           name: generated-notebooks