From sklearn 1.5.0, pandas is a dependency for `fetch_openml`

[VincentRouvreau]

In src/python/example/cubical_complex_sklearn_itf.py, we use sklearn fetch_openml to fetch MNIST dataset (the one with a better resolution).

Issue

But, from sklearn 1.5.0, pandas is a dependency for fetch_openml.

Solution

Add pandas in test-requirements.txt in gudhi-deploy repo and an entry in the installation documentation as it becomes an optional third parties library.