Fix 1753 fork criteria

[Praniti1594]

🗒️ Description

This PR explicitly annotates the FORK_CRITERIA variable with the ForkCriteria supertype across all fork definition files (src/ethereum/forks/*/init.py). This addresses a type-checking issue where the narrower type (e.g., ByBlockNumber) was being inferred, which could lead to API breakage when transitioning to a broader type (e.g., ByTimestamp).

🔗 Related Issues or PRs

Fixes #1753

✅ Checklist

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

  uvx tox -e 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 adding an entry to CHANGELOG.md.
• 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.

Cute Animal Picture