Formulaic

This is identical to v1.0.0, but with the package status marked to production/stable rather than beta [**facepalm**].

This is the first officially stable release of formulaic, with a relatively small diff from the 0.6.x series.

**Breaking changes:**

* Python tokens are now canonically formatted (see below).
* Methods deprecated during the 0.x series have been removed: `Formula.terms`,
`ModelSpec.feature_names`, and `ModelSpec.feature_indices`.

**New features and enhancements:**

* Python tokens are now sanitized and canonically formatted to prevent
ambiguities and better align with `patsy`.
* Added official support for Python 3.12 (no code changes were necessary).
* Added the `hashed` transform for categorically encoding deterministically
hashed representations of a dataset. [Contributed by rishi-kulkarni]

**Bugfixes and cleanups:**

* Fixed transform state not propagating correctly when Python code tokens were
not canonically formatted.
* Literals in formulae will no longer be silently ignored, and feature scaling
is now fully supported.
* Improved code parsing and formatting utilities and dropped the requirement for
`astor` for Python 3.9 and newer.
* Fixed all warnings emitted during unit tests.

**Documentation:**

* Removed incompleteness warnings.
* Added some lightweight developer documents.
* Fixed some broken links.

This is minor release with one important bugfix.

**Bugfixes and cleanups:**

* Fixes a regression introduced by 0.6.4 whereby missing variables will be
silently dropped from the formula., rather than raising an exception.

This is a minor release with several important bugfixes.

**Bugfixes and cleanups:**

* Fixed intercept terms sorting after other features (by not counting literal
factors toward the degree of a term). 156
* Fixed a regression in 0.6.4 around quoted field names in Python evaluations. 154
* Fixed detection and dropping of null rows in sparse datasets. 155
* Fixed `poly()` transforms operating on datasets that include null values. 155
* Arguments can now be passed when running the unit tests using `hatch run tests`.

This is a minor release with several new features and cleanups.

**New features and enhancements:**

* Added support for keeping track of the source of variables being used to
evaluate a formula. Refer to the `ModelSpec` documentation for more details.

**Bugfixes and cleanups:**

* All functions and methods now have type signatures that are statically checked
during unit testing.
* Removed `OrderedDict` usage, since Python guarantees the orderedness of
dictionaries in Python 3.7+.
* Suppress terms/factors in model matrices for which the factors evaluate to
`None`.

This is a minor release with a bugfix.

**Bugfixes and cleanups:**

* Fixed a regression introduced in the previous release when materializing categorical encodings of variables with no levels.