joblib missing from requirements

[clausmichele]

The recent merge of aggregate_spatial introduced the requirement of joblib, which is not installed since it's missing from the pyproject.toml.
Please add it as soon as possible, otherwise the code can't be used directly but joblib must be installed manually.

@masawdah @GeraldIr @ValentinaHutter

[masawdah]

I fixed that with this new pull request #217 and used the new XVEC functionality for spatial aggregation.