Add news entry

Author: johnslavik

Misc/NEWS.d/next/Library/2026-01-13-15-56-03.gh-issue-132604.lvjNTr.rst

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+It is deprecated to call :func:`isinstance` and :func:`issubclass` checks on
+:class:`typing.Protocol` classes that were not explicitly decorated
+with :func:`typing.runtime_checkable` after subclassing  runtime-checkable
+protocol classes. This will throw a :exc:`TypeError` in Python 3.20.
+Contributed by Bartosz Sławecki.