Pysr

What's Changed
* Automated update to backend: v0.22.2 by MilesCranmer in https://github.com/MilesCranmer/PySR/pull/404


Backend changes

- Expand aqua test suite (MilesCranmer/SymbolicRegression.jl246) (MilesCranmer)
- Return more descriptive errors for poorly defined operators (MilesCranmer/SymbolicRegression.jl247) (MilesCranmer)

**Backend Changelog**: [Diff since v0.22.1](https://github.com/MilesCranmer/SymbolicRegression.jl/compare/v0.22.1...v0.22.2)
**PySR Changelog**: https://github.com/MilesCranmer/PySR/compare/v0.16.0...v0.16.1

What's Changed
* Backend version update in https://github.com/MilesCranmer/PySR/pull/400. Includes:
* Algorithmic improvements to batching
* Code quality improvements (some method ambiguities, old exports)

Backend changes

* (**Algorithm modification**) Evaluate on fixed batch when building per-population hall of fame in https://github.com/MilesCranmer/SymbolicRegression.jl/pull/243
* This only affects searches that use `batching=true`. It results in improved searches on large datasets, as the "winning expression" is not biased towards an expression that landed on a lucky batch.
* Note that this only occurs within an iteration. Evaluation on the entire dataset still happens at the end of an iteration and those loss measurements are used for absolute comparison between expressions.
* (**Algorithm modification**) Deprecates the `fast_cycle` feature in https://github.com/MilesCranmer/SymbolicRegression.jl/pull/243. Use of this parameter will have no effect.
* Was removed to ease maintenance burden and because it doesn't have a use. This feature was created early on in development as a way to get parallelism within a population. It is no longer useful as you can parallelize across populations.
* Add Aqua.jl to test suite in https://github.com/MilesCranmer/SymbolicRegression.jl/pull/245 for code quality control
* CompatHelper: bump compat for DynamicExpressions to 0.12, (keep existing compat) in https://github.com/MilesCranmer/SymbolicRegression.jl/pull/242
* Is able to avoids method invalidations when using operators to construct expressions manually by modifying a global constant mapping of operator => index, rather than `eval`-ing new operators.
* This only matters if you were using operators to build trees, like `x1 + x2`. All internal search code uses `Node()` explicitly to build expressions, so did not rely on method invalidation at any point.


**Backend Changelog**: https://github.com/MilesCranmer/SymbolicRegression.jl/compare/v0.21.5...v0.22.1

**PySR Changelog**: https://github.com/MilesCranmer/PySR/compare/v0.15.4...v0.16.0

What's Changed
* Warn user when using power laws by MilesCranmer in https://github.com/MilesCranmer/PySR/pull/399
* This seems like the most common configuration mistake in PySR: using the `^` operator without setting `constraints`, leading to extremely complex expressions with poor generalization properties. Thus, this warning will let the user know about it if they set up `^` without constraints.


**Full Changelog**: https://github.com/MilesCranmer/PySR/compare/v0.15.3...v0.15.4

What's Changed
* Use unicode in printing without needing to decode by MilesCranmer in https://github.com/MilesCranmer/PySR/pull/398


**Full Changelog**: https://github.com/MilesCranmer/PySR/compare/v0.15.2...v0.15.3

What's Changed
* Ensure files are read as utf-8 on all operating systems by MilesCranmer in https://github.com/MilesCranmer/PySR/pull/396


**Full Changelog**: https://github.com/MilesCranmer/PySR/compare/v0.15.1...v0.15.2

What's Changed
* Fix compat with old scikit-learn versions by MilesCranmer in https://github.com/MilesCranmer/PySR/pull/393


**Full Changelog**: https://github.com/MilesCranmer/PySR/compare/v0.15.0...v0.15.1