Clean metadata from notebooks during pre-commit

[NicolaCourtier]

Feature description

Remove unnecessary metadata from the example notebooks prior to git commit.

Motivation

To simplify the review process by ensuring that only material changes to the example notebooks and their output are shown.

Possible implementation

Add the nbstripout pre-commit hook from: https://github.com/kynan/nbstripout.

Additional context

No response