chore(specs): avoid using an itertools object in the BaseTest pydantic model

[danceratopz]

🗒️ Description

Our BaseTest spec model, which is used by all test formats has a field _t8n_call_counter which is typed as Iterator[int] and set to be an itertools.count() object.

When pydantic does a deepcopy of the model upon validation this itertools object triggers the following deprecation warning:

tests/istanbul/eip1344_chainid/test_chainid.py: 24 warnings
  /usr/lib/python3.12/copy.py:151: DeprecationWarning: Pickle, copy, and deepcopy support will be removed from itertools in Python 3.14.
    rv = reductor(4)

This change removes these deprecation warnings.

To determine the source of the warning, I told pytest to treat DeprecationWarning as an error:

fill tests/istanbul/eip1344_chainid/ --fork=Cancun -m state_test -v -W error::DeprecationWarning

->

tests/istanbul/eip1344_chainid/test_chainid.py::test_chainid[fork_Cancun-state_test] FAILED                                                                                                                    [1/1]
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> traceback >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
tests/istanbul/eip1344_chainid/test_chainid.py:42: in test_chainid
    state_test(env=env, pre=pre, post=post, tx=tx)
src/pytest_plugins/filler/filler.py:701: in __init__
    super(BaseTestWrapper, self).__init__(*args, **kwargs)
.venv/lib/python3.12/site-packages/pydantic/_internal/_model_construction.py:125: in wrapped_model_post_init
    init_private_attributes(self, context)
.venv/lib/python3.12/site-packages/pydantic/_internal/_model_construction.py:339: in init_private_attributes
    default = private_attr.get_default()
.venv/lib/python3.12/site-packages/pydantic/fields.py:1166: in get_default
    return _utils.smart_deepcopy(self.default) if self.default_factory is None else self.default_factory()
.venv/lib/python3.12/site-packages/pydantic/_internal/_utils.py:345: in smart_deepcopy
    return deepcopy(obj)  # slowest way when we actually might need a deepcopy
/usr/lib/python3.12/copy.py:151: in deepcopy
    rv = reductor(4)
E   DeprecationWarning: Pickle, copy, and deepcopy support will be removed from itertools in Python 3.14.

🔗 Related Issues

Fixes #1035:

• shall we fix fill warnings? #1035

✅ Checklist

• All: Set appropriate labels for the changes.
• All: Considered squashing commits to improve commit history.
• All: Added an entry to CHANGELOG.md.

[danceratopz]

There are no 🥒, copy, deepcopy warnings in the fill warnings summary here: https://github.com/ethereum/execution-spec-tests/actions/runs/14343348442/job/40207802205?pr=1414#step:5:229

For example, compare with a previous run without the fix: https://github.com/ethereum/execution-spec-tests/actions/runs/14343126724/job/40207082724#step:5:228

[marioevz]

LGTM, thanks!