Development mode: DEPRECATION: Legacy editable install of ece2cmor3

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When using a latest mamba install followed by an ece2cmor3 install for the developer mode with:

pip install -e .

A deprecation message concerning the editable install (the developer -e) mode is given. Which will take final effect with pip 25.0 somewhere in the first quarter of 2025. Note that the developer (the -e) mode itself will remain.

This mode is relevant for most of us nowadays as many of us use this mode to enable non official cmor additions in our cmorisation.

Some further reading and suggestions are given by:
https://ichard26.github.io/blog/2024/08/whats-new-in-pip-24.2/
pypa/pip#11457

I tried to add the pyproject.toml file with the three default lines, this did not work. Obviously I have not understood the full case properly so far.