feat: add python-benedict[schema] optional dependency (pydantic v2)

[Copilot]

Introduces optional Pydantic v2-based schema validation/type coercion for python-benedict's I/O layer via a new schema= kwarg, and wires it into packaging, docs, and tests.

Describe your changes

• Added benedict/utils/schema_util.py with apply_schema() and require_schema() using try/except ImportError for optional pydantic detection; added # pragma: no cover to the except ImportError: branch
• Applied apply_schema() in io_util.decode/encode when schema is provided
• Added schema optional extra (pydantic>=2,<3) in pyproject.toml and included it in the all extra
• Updated README to document the new schema optional extra
• Added schema test suite covering from_json, from_yaml, from_toml, from_ini, from_xml, from_csv, from_xls, and corresponding to_* methods
• Pinned pydantic >= 2.0.0, < 3.0.0 in requirements.txt; removed the unnecessary zipp pin
• Merged latest changes from main

Related issue
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Checklist before requesting a review

• I have performed a self-review of my code.
• I have added tests for the proposed changes.
• I have run the tests and there are not errors.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 98.32%. Comparing base (4073f83) to head (361b195).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #565      +/-   ##
==========================================
+ Coverage   98.31%   98.32%   +0.01%     
==========================================
  Files          63       64       +1     
  Lines        2368     2389      +21     
==========================================
+ Hits         2328     2349      +21     
  Misses         40       40              

Flag	Coverage Δ
unittests	98.32% <100.00%> (+0.01%)	⬆️

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[Copilot]

Pull request overview

This PR introduces optional Pydantic v2-based schema validation/type coercion for python-benedict’s normalized I/O layer via a new schema= kwarg, and wires it into packaging/docs/tests.

Changes:

• Add benedict.utils.schema_util.apply_schema() + new require_schema() extra gate, and apply it in io_util.decode/encode when schema is provided.
• Add the new schema optional dependency (pydantic v2) in pyproject.toml and update README documentation.
• Add a dedicated schema test suite covering multiple from_* / to_* I/O methods.

Reviewed changes

Copilot reviewed 6 out of 7 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/dicts/io/test_schema.py	Adds schema-focused tests for validation, coercion, and extra-field stripping across multiple I/O methods.
requirements.txt	Adds pydantic v2 to the repo’s test/dev dependency set (used by tox).
pyproject.toml	Introduces the new schema extra (pydantic v2).
benedict/utils/schema_util.py	Adds a lightweight schema application helper gated by the schema extra.
benedict/extras.py	Adds require_schema() to enforce schema extra installation.
benedict/dicts/io/io_util.py	Plumbs schema through decode/encode, applying schema validation when provided.
README.md	Documents the schema kwarg and adds [schema] to the optional requirements list.

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[fabiocaccamo]

zipp requirement must be clamped or fixed using ==

[Copilot]

zipp requirement must be clamped or fixed using ==

Fixed in 4cbdf47 — zipp is now pinned to == 3.23.1.

[fabiocaccamo]

@copilot you must also update from main branch.

[Copilot]

@copilot you must also update from main branch.

Done in 361b195 — merged the latest changes from main into this branch.