Remember to list any API changes below in `doc/release/release_dev.rst`.

Version 0.17
------------

* Finalize ``skimage.future.manual_segmentation`` API.

Version 0.21
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* In ``skimage/filters/lpi_filter.py``, remove the deprecated function
  inverse().
* Set `channel_axis=None` in `skimage._shared.filters.gaussian` and remove
  `skimage._shared.filters._PatchClassRepr`,
  `skimage/_shared/filters.ChannelAxisNotSet`, and
  `skimage.filters.tests.test_gaussian.test_deprecated_automatic_channel_detection`.
  Also remove the associated warning in `skimage._shared.filters.gaussian`'s
  docstring.
* Deprecate ``return_error`` argument in
  ``skimage.registration.phase_cross_correlation``. The function should always
  return a tuple of (shift, error, phasediff).
  Update ``test_phase_cross_correlation_deprecation``, too.
* Remove ``skimage/future/graph`` and ``skimage/future/tests/test_graph`.
  Remove the ``future/graph`` entry in ``skimage/conftest.py::collect_ignore``.
  Remove the ``r'\.future.graph$'`` entry added to
  ``docwriter.package_skip_patterns`` in
  ``doc/tools/build_modref_templates.py``.

Other (2022)
------------
* Remove custom code for ignored warning in `skimage/_shared/testing.py` relating
  to (sparse) matricies (instead of arrays).
