fix(tests): register JSON fixture fork marker

[JackCC703]

🗒️ Description

Register the fork(name) pytest marker used by JSON fixture tests.

JSON fixture collection adds pytest.mark.fork(...) to collected tests, but the marker was not registered in the root pytest configuration. This caused PytestUnknownMarkWarning during pytest runs. Registering the marker in pyproject.toml silences the warning without changing test behavior.

🔗 Related Issues or PRs

Fixes #1407.

✅ Checklist

• All: Ran fast static checks to avoid unnecessary CI fails, see also Code Standards and Enabling Pre-commit Checks:

  just static

• All: PR title adheres to the repo standard - it will be used as the squash commit message and should start type(scope):.
• All: Considered updating the online docs in the ./docs/ directory.
• All: Set appropriate labels for the changes (only maintainers can apply labels).
• Tests: Ran mkdocs serve locally and verified the auto-generated docs for new tests in the Test Case Reference are correctly formatted.
• Tests: For PRs implementing a missed test case, update the post-mortem document to add an entry the list.
• Ported Tests: All converted JSON/YML tests from ethereum/tests or tests/static have been assigned @ported_from marker.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 93.22%. Comparing base (3f888bc) to head (3ec94e0).

Additional details and impacted files

@@               Coverage Diff                @@
##           forks/amsterdam    #3053   +/-   ##
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  Coverage            93.22%   93.22%           
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  Files                  624      624           
  Lines                36926    36926           
  Branches              3377     3377           
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  Hits                 34424    34424           
  Misses                1708     1708           
  Partials               794      794           

Flag	Coverage Δ
unittests	93.22% <ø> (ø)

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[danceratopz]

Sorry, #1407 is an old issue and I don't think it's required any longer. Could you share the command you're using and the warnings that this change fixes? I.e., can you still reproduce them locally before this change. I had a quick go and couldn't create the warnings.

[danceratopz]

I'm not sure this would actually match any marker as name is not a valid fork name (as noted in #1407).

[JackCC703]

Thank you. I updated the marker registration from fork(name) to fork: ... to
avoid implying that name is a fork value.

[JackCC703]

Oh, Sorry. I think the difference is that my checkout has generated JSON fixtures under tests/json_loader/fixtures/, which are ignored by git. A clean checkout does not have those files, so the warning won't appear unless that generated fixture collection workflow is used.

So this PR only fixes the warning for collecting generated JSON fixtures, not for a clean default pytest run. Since the issue is old, if that workflow is no longer considered supported or relevant, I'm happy to close this PR.

[JackCC703]

On origin/forks/amsterdam, with a generated JSON fixture present under
tests/json_loader/fixtures/, I can reproduce it with:

.venv/bin/pytest --collect-only -q tests/json_loader/fixtures/blockchain_tests/for_frontier/frontier/validation/transaction/sender_balance.json -W "error::pytest.PytestUnknownMarkWarning"

This fails before the change with:

E   pytest.PytestUnknownMarkWarning: Unknown pytest.mark.fork - is this a typo?  You can register custom marks to avoid this warning

The warning is triggered from:

self.add_marker(pytest.mark.fork(self.fork_name))

in tests/json_loader/helpers/load_blockchain_tests.py.

After this PR, the same command passes with PytestUnknownMarkWarning
configured to fail the run, which confirms that the warning is no longer emitted.