Python 3.12 support

[veenstrajelmer]

Issue addressed

Fixes #540

Explanation

Just checking if all tests pass with Python 3.12:

• added py312 to pixi tests
• there are many DeprecationWarnings that cause ERRORS, for instance: ERROR tests/data_catalog/test_data_catalog.py::test_export_global_datasets_overrwite - DeprecationWarning: Python 3.14 will, by default, filter extracted tar archives and reject files or modify their metadata. Use the filter argument to control this behavior. - This comes from pooch.retrieve() or actually the passed processor=pooch.Untar which calls tar_file.extractall(). I hoped to resolve it by passing a filter='data' argument to the processer pooch.Untar, but this is not supported. Instead, I have added this to filterwarnings in pyproject.toml.
• after the changes above, the tests pass in the test workflow.

General Checklist

• Updated tests or added new tests
• Branch is up to date with main
• Tests & pre-commit hooks pass
• Updated documentation >> yes, toml and readme are updated so supported versions will be visible on pypi and github after the next release (via classifiers and readme badge)
• Updated changelog.rst >> no, to avoid conflicts, could be "Added support for Python 3.12 (Python 3.12 support #1094)"

Data/Catalog checklist

• data/catalogs/predefined_catalogs.yml has not been modified.
• None of the old data_catalog.yml files have been chagned
• data/chagnelog.rst has been updated
• new file uses LF line endings (done automatically if you used update_versions.py)
• New file has been tested locally
• Tests have been added using the new file in the test suite