The ``item`` parameter of ``pytest_warning_captured`` hook is now documented as deprecated. We realized only after
the ``3.8`` release that this parameter is incompatible with ``pytest-xdist``.

Our policy is to not deprecate features during bugfix releases, but in this case we believe it makes sense as we are
only documenting it as deprecated, without issuing warnings which might potentially break test suites. This will get
the word out that hook implementers should not use this parameter at all.

In a future release ``item`` will always be ``None`` and will emit a proper warning when a hook implementation
makes use of it.