HTTP error 429 for test datasets

**Describe the bug**
We get an HTTP error 429 from Zenodo now.

**To Reproduce**

Steps to reproduce the behavior:

1. pytest tests/test_available_data.py

**Expected behavior**

No HTTP error.

**System [please complete the following information]:**

- OS: MacOS 15.5; GitHub actions.
- Language Version: Python 3.13
- Virtual environment: conda

