feat: add the ability to run examples with pytest

[jakelorocco]

Add pytest docs so that you can run most of the examples as a single pytest run. I had to modify a few tests to get them to be runnable from any directory and without user input.

Also updated our codespell precommit hook so that we can use #ignore:codespell syntax for individual lines.

Found and fixed bugs as a part of this:

• The huggingface version of granite guardian was passing a duplicate model option which was causing errors
• Added __copy__ and __deepcopy__ dunder methods to ModelOutputThunk to prevent errors when generating with sampling strategies since sampling strategies copy actions
• Added a raises clause to the docstring of generative slots since validation can occasionally fail

Output looks like regular pytest and identifies the example file:

================================================================ test session starts =================================================================
platform darwin -- Python 3.12.0, pytest-8.4.2, pluggy-1.6.0
rootdir: /Users/jake/code/mellea
configfile: pyproject.toml
plugins: asyncio-1.2.0, anyio-4.11.0, Faker-37.6.0
asyncio: mode=Mode.AUTO, debug=False, asyncio_default_fixture_loop_scope=None, asyncio_default_test_loop_scope=function
collected 45 items

docs/examples/agents/react.py .                                                                                                                [  2%]

Some of the examples have to be skipped since they can't easily be run in a pytest compatible way. When pytest runs on the docs directory, a reminder is output to run those files manually:

================================================================== Skipped Examples ==================================================================
Examples with the following names were skipped because they cannot be easily run in the pytest framework; please run them manually:
101_example.py
mcp_example.py
client.py
__init__.py
simple_rag_with_filter.py

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[avinash2692]

FYI: you could do this with nbmake https://github.com/treebeardtech/nbmake

[avinash2692]

LGTM apart from a couple of things:

• might make sense to add nbmake in this PR before merging so that we have notebooks also covered in the tests

[avinash2692]

Do you want all conftest.py to be in the same place. Not sure how the hierarchy works with pytest

[jakelorocco]

Maybe eventually, but I don't think so right now:

• I don't think we always want the examples to run by default. We would have to write new code to disable them on github runner's, etc...
• The tests are different enough that they should almost always be run separately

[jakelorocco]

Also, it requires changing how the pytest command is invoked. I think that change is fine, but I we should think about when we want to run the examples, etc...

[jakelorocco]

LGTM apart from a couple of things:

• might make sense to add nbmake in this PR before merging so that we have notebooks also covered in the tests

I added nbmake to the comment documenting how to test the notebooks. I think we should add notebook testing eventually but I think this PR is fine without it. To run the notebooks with nbmake requires rewriting the notebooks to avoid background processes.

[avinash2692]

LGTM. I'll look into addinf nbmake is a separate PR.