Remove scipy deprecation warnings

[eendebakpt]

Description

Remove scipy deprecation in learner2D.py

DeprecationWarning: Delaunay attribute 'vertices' is deprecated in favour of 'simplices' and will be removed in Scipy 1.11.0.

Checklist

• Fixed style issues using pre-commit run --all (first install using pip install pre-commit)
• pytest passed (does not work locally)

Type of change

Check relevant option(s).

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• (Code) style fix or documentation update
• This change requires a documentation update

[basnijholt]

Thanks a lot!

Do you know whether this will work with "older" versions of scipy?

[basnijholt]

OK this was deprecated in 2012 (scipy/scipy#377) 😂

We can safely merge.