Log Message:
py-xarray: updated to 0.18.2

v0.18.2 (19 May 2021)
---------------------
This release reverts a regression in xarray's unstacking of dask-backed arrays.

v0.18.1 (18 May 2021)
---------------------
This release is intended as a small patch release to be compatible with the new
2021.5.0 ``dask.distributed`` release. It also includes a new
``drop_duplicates`` method, some documentation improvements, the beginnings of
our internal Index refactoring, and some bug fixes.

New Features

- Implement :py:meth:`DataArray.drop_duplicates`
  to remove duplicate dimension values (:pull:`5239`).
- Allow passing ``combine_attrs`` strategy names to the ``keep_attrs`` parameter of
  :py:func:`apply_ufunc` (:pull:`5041`)
- :py:meth:`Dataset.interp` now allows interpolation with non-numerical datatypes,
  such as booleans, instead of dropping them. (:issue:`4761` :pull:`5008`).
- Raise more informative error when decoding time variables with invalid \ 
reference dates.
  (:issue:`5199`, :pull:`5288`).

Bug fixes

- Opening netCDF files from a path that doesn't end in ``.nc`` without supplying
  an explicit ``engine`` works again (:issue:`5295`), fixing a bug introduced in
  0.18.0.

Documentation

- Clean up and enhance docstrings for the :py:class:`DataArray.plot` and \ 
``Dataset.plot.*``
  families of methods (:pull:`5285`).

- Explanation of deprecation cycles and how to implement them added to contributors
  guide. (:pull:`5289`)