Dwave-greedy

New Features
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- `greedy.SteepestDescentComposite`, a greedy descent post-processing composite

Implements a fast greedy solver for binary quadratic models: [`greedy.SteepestDescentSolver()`](https://docs.ocean.dwavesys.com/projects/greedy/en/latest/reference/samplers.html#steepestdescentsolver).

Fixes
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- RtD builds correctly
- CircleCI triggers `rcX` deploys

First public release.

Includes `greedy.SteepestDescentSolver`.