Spec-classes

This is a minor bugfix release with one fix:

* [Fix callable attributes assigned as defaults via staticmethods.](https://github.com/matthewwardrop/spec-classes/commit/2d63efb5e65fb7f455acdeba22447e12408d1b93)

This release comes with a few small new features.

**New features and enhancements**:

* Added `classproperty` for `spec_property` like behavior for classmethods.
* Add support for emitting warnings when properties are overridden (use `warn_on_override` in `spec_property` or `classproperty` constructor).
* Made `MISSING` usable in type annotations, and add `EMPTY` and `SENTINEL` variations.

A few minor improvements:

* Improve helpfulness of error messages when errors are raised from collections during mutation.
* Suppress deprecation (and other) warnings while generating `AttrSpec`s during class bootstrapping.

**Full Changelog**: https://github.com/matthewwardrop/spec-classes/compare/v1.3.0...v1.3.1

This releases adds a few small features, and comes with official support for Python 3.11 and 3.12.

What's Changed
* Added official support for Python 3.11 and 3.12
* Renamed `AttrProxy` to `Alias`, and add `DeprecatedAlias`.
* Added `dataclass_transform` annotation from mypy type checking.


**Full Changelog**: https://github.com/matthewwardrop/spec-classes/compare/v1.2.6...v1.3.0

This is a minor patch release that properly fixes the bug addressed by v1.2.5. That is: a race-condition during copying when used in a multi-threaded context. This would have manifested as a KeyError: <class 'module'> during copying.

The previous solution didn't work because we inadvertently constructed multiple locks per process, which defeats the point of the lock.

This is a minor patch release that fixes a race-condition during copying when used in a multi-threaded context. This would have manifested as a `KeyError: <class 'module'>` during copying.