Wrong `__version__` in `__init__.py`

Hi,

I've noticed the wrong version number set for `__version__` in `__init.py__`.

One solution would be to use `importlib.metadata.version('cmocean')` to always the correct version number taken from the `setup.py`.

If that is something wanted, I am happy to do a PR for it :)

Inspect __init__.py and setup.py to compare the current __version__ value with the package version metadata. Evaluate the proposed importlib.metadata.version('cmocean') approach, and confirm that the reported version matches the version defined for the package.

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