Nano-utils

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* Fixed an issue with building wheels.

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* Added ``UniqueLoader``, a `pyyaml Loader <https://pyyaml.org/wiki/PyYAMLDocumentation>`_ that dissallows duplicate keys.
* Added three functions for recursivvelly iterating through `hdf5 <https://docs.h5py.org/en/stable/>`_ files/groups:
``recursive_keys()``, ``recursive_values()`` and ``recursive_items()``.
* Renamed ``DtypeLike`` to ``DTypeLike``.

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* Bump the setup-python version to `v2`.
* Enable tests for Python 3.9.

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* Bump the Cancel Workflow Action version to `0.4.1`.

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* Added aliases for the following ``numpy.typing`` annotations:
``ArrayLike``, ``DtypeLike`` & ``ShapeLike``.
* Fixed an issue with the license in ``MANIFEST.in``.
* Enable `Cancel Workflow Action <https://github.com/marketplace/actions/cancel-workflow-action>`_ for the unit tests.
* Added tests for building wheels.

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* Validate the passed path-/file-like object in `AbstractFileContainer.read()` and `.write()`.
* Enabled the readthedocs Autobuild Documentation for Pull Requests option.