Tutorials not up to date with postopus interface

The visualization tutorial is not up to date: https://octopus-code.org/documentation/main/tutorial/basics/visualization/

The postopus interface has changed in version 0.3.0, see https://gitlab.com/octopus-code/postopus/-/blob/main/CHANGELOG.rst

density = run.default.scf.density.get_converged(source="cube")

needs to be

density = run.default.scf.density(source="cube")