Miscellaneous improvements for 2023-W43

[khaeru]

• Address recent CI failures occurring with xarray >= 2023.10.0 on Python ≥3.9:

  ___________________ test_interpolate[sparsedataarray-shape0] ___________________
  
  genno/core/sparsedataarray.py:66: in dense
    return self.da._replace(variable=self.da.variable._to_dense())
  _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 
  
  self = <xarray.Variable ()>
  array(0.44617429)
  Attributes:
    _unit:    kilogram
  
    def _to_dense(self) -> Self:
        """
        Change backend from sparse to np.array
        """
        from xarray.namedarray._typing import _sparsearrayfunction_or_api
  
        if isinstance(self._data, _sparsearrayfunction_or_api):
            # return self._replace(data=self._data.todense())
            data_: np.ndarray[Any, Any] = self._data.todense()
            return self._replace(data=data_)
        else:
  >           raise TypeError("self.data is not a sparse array")
  E           TypeError: self.data is not a sparse array
  
  /opt/hostedtoolcache/Python/3.11.6/x64/lib/python3.11/site-packages/xarray/namedarray/core.py:813: TypeError

• [x] Add convenience methods similar to add_mul() to automatically determine dimensionality of result automatically for: add(), div(), sub(), and any other basic arithimetic operations.
• [x] Test binops, including unit handling: +, -, /, *.
• [x] Extend Key.__div__ to handle k / ("a", "b"), k1 / k2.
• [x] Extend Key.__mul__ to handle k * ("a", "b"), k1 * k2.
• Extend testing and confirmed support to Python 3.12.
• Replace black formatting with ruff format.

PR checklist

• [x] Checks all ✅
• [x] Update documentation
• [x] Update doc/whatsnew.rst

[codecov-commenter]

Codecov Report

Merging #105 (bb88a90) into main (0fff94a) will not change coverage. The diff coverage is 100.00%.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #105 +/- ## ========================================== Coverage 100.00% 100.00% ========================================== Files 47 48 +1 Lines 3926 4041 +115 ========================================== + Hits 3926 4041 +115 ``` | [Files](https://app.codecov.io/gh/khaeru/genno/pull/105?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Paul+Natsuo+Kishimoto) | Coverage Δ | | |---|---|---| | [genno/caching.py](https://app.codecov.io/gh/khaeru/genno/pull/105?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Paul+Natsuo+Kishimoto#diff-Z2Vubm8vY2FjaGluZy5weQ==) | `100.00% <ø> (ø)` | | | [genno/compat/graphviz.py](https://app.codecov.io/gh/khaeru/genno/pull/105?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Paul+Natsuo+Kishimoto#diff-Z2Vubm8vY29tcGF0L2dyYXBodml6LnB5) | `100.00% <ø> (ø)` | | | [genno/compat/pint.py](https://app.codecov.io/gh/khaeru/genno/pull/105?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Paul+Natsuo+Kishimoto#diff-Z2Vubm8vY29tcGF0L3BpbnQucHk=) | `100.00% <ø> (ø)` | | | [genno/compat/plotnine/plot.py](https://app.codecov.io/gh/khaeru/genno/pull/105?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Paul+Natsuo+Kishimoto#diff-Z2Vubm8vY29tcGF0L3Bsb3RuaW5lL3Bsb3QucHk=) | `100.00% <100.00%> (ø)` | | | [genno/compat/pyam/\_\_init\_\_.py](https://app.codecov.io/gh/khaeru/genno/pull/105?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Paul+Natsuo+Kishimoto#diff-Z2Vubm8vY29tcGF0L3B5YW0vX19pbml0X18ucHk=) | `100.00% <ø> (ø)` | | | [genno/compat/pyam/operator.py](https://app.codecov.io/gh/khaeru/genno/pull/105?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Paul+Natsuo+Kishimoto#diff-Z2Vubm8vY29tcGF0L3B5YW0vb3BlcmF0b3IucHk=) | `100.00% <100.00%> (ø)` | | | [genno/compat/sdmx.py](https://app.codecov.io/gh/khaeru/genno/pull/105?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Paul+Natsuo+Kishimoto#diff-Z2Vubm8vY29tcGF0L3NkbXgucHk=) | `100.00% <ø> (ø)` | | | [genno/compat/xarray.py](https://app.codecov.io/gh/khaeru/genno/pull/105?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Paul+Natsuo+Kishimoto#diff-Z2Vubm8vY29tcGF0L3hhcnJheS5weQ==) | `100.00% <100.00%> (ø)` | | | [genno/computations.py](https://app.codecov.io/gh/khaeru/genno/pull/105?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Paul+Natsuo+Kishimoto#diff-Z2Vubm8vY29tcHV0YXRpb25zLnB5) | `100.00% <100.00%> (ø)` | | | [genno/config.py](https://app.codecov.io/gh/khaeru/genno/pull/105?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Paul+Natsuo+Kishimoto#diff-Z2Vubm8vY29uZmlnLnB5) | `100.00% <100.00%> (ø)` | | | ... and [21 more](https://app.codecov.io/gh/khaeru/genno/pull/105?src=pr&el=tree-more&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Paul+Natsuo+Kishimoto) | |