Marshmallow

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Features:

- Raise ``ValueError`` if an invalid value is passed to the ``unknown``
argument (:issue:`1721`, :issue:`1732`).
Thanks :user:`sirosen` for the PR.

Other changes:

- Set lower bound for ``packaging`` requirement (:issue:`1957`).
Thanks :user:`MatthewNicolTR` for reporting and thanks :user:`sirosen` for the PR.
- Improve warning messages by passing ``stacklevel`` (:pr:`1986`).
Thanks :user:`tirkarthi` for the PR.

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Features:

- Allow passing a ``dict`` to ``fields.Nested`` (:pr:`1935`).
Thanks :user:`sirosen` for the PR.

Other changes:

- Address distutils deprecation warning in Python 3.10 (:pr:`1903`).
Thanks :user:`kkirsche` for the PR.
- Add py310 to black target-version (:pr:`1921`).
- Drop support for Python 3.6 (:pr:`1923`).
- Use postponed evaluation of annotations (:pr:`1932`).
Thanks :user:`Isira-Seneviratne` for the PR.

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Bug fixes:

- Fix publishing type hints per `PEP-561 <https://www.python.org/dev/peps/pep-0561/>`_
(:pr:`1905`). Thanks :user:`bwindsor` for the catch and patch.

*******************

Bug fixes:

- Fix ``fields.TimeDelta`` serialization precision (:issue:`1865`).
Thanks :user:`yarsanich` for reporting.

Other changes:

- Fix type-hints for ``data`` arg in ``Schema.validate`` to accept
list of dictionaries (:issue:`1790`, :pr:`1868`).
Thanks :user:`yourun-proger` for PR.
- Improve warning when passing metadata as keyword arguments (:pr:`1882`).
Thanks :user:`traherom` for the PR.
- Don't build universal wheels. We don't support Python 2 anymore.
(:issue:`1860`) Thanks :user:`YKdvd` for reporting.
- Make the build reproducible (:pr:`1862`).
- Drop support for Python 3.5 (:pr:`1863`).
- Test against Python 3.10 (:pr:`1888`).

*******************

Features:

- Replace ``missing``/``default`` field parameters with
``load_default``/``dump_default`` (:pr:`1742`).
Thanks :user:`sirosen` for the PR.

Deprecations:

- The use of ``missing``/``default`` field parameters is deprecated and will be
removed in marshmallow 4. ``load_default``/``dump_default`` should be used
instead.

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Bug fixes:

- Don't expose ``Field``\s as ``Schema`` attributes. This reverts a change
introduced in 3.12.0 that causes issues when field names conflict with
``Schema`` attributes or methods. ``Fields``\s are still accessible on a
``Schema`` instance through the ``fields`` attribute. (:pr:`1843`)