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

• Add convenience methods similar to add_mul() to automatically determine dimensionality of result automatically for: add(), div(), sub(), and any other basic arithimetic operations.
• Test binops, including unit handling: +, -, /, *.
• Extend Key.__div__ to handle k / ("a", "b"), k1 / k2.
• 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

• Checks all ✅
• Update documentation
• 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

@@            Coverage Diff             @@
##              main      #105    +/-   ##
==========================================
  Coverage   100.00%   100.00%            
==========================================
  Files           47        48     +1     
  Lines         3926      4041   +115     
==========================================
+ Hits          3926      4041   +115     

Files	Coverage Δ
genno/caching.py	100.00% <ø> (ø)
genno/compat/graphviz.py	100.00% <ø> (ø)
genno/compat/pint.py	100.00% <ø> (ø)
genno/compat/plotnine/plot.py	100.00% <100.00%> (ø)
genno/compat/pyam/__init__.py	100.00% <ø> (ø)
genno/compat/pyam/operator.py	100.00% <100.00%> (ø)
genno/compat/sdmx.py	100.00% <ø> (ø)
genno/compat/xarray.py	100.00% <100.00%> (ø)
genno/computations.py	100.00% <100.00%> (ø)
genno/config.py	100.00% <100.00%> (ø)
... and 21 more