Add news fragment

Author: abravalheri

newsfragments/4840.feature.rst

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+Deprecated ``project.license`` as a TOML table in
+``pyproject.toml``. Users are expected to move towards using
+``project.license-files`` and/or SPDX expressions (as strings) in
+``pyproject.license``.
+See :pep:`PEP 639 <639#deprecate-license-key-table-subkeys>`.