- update to 3.2.0:
* Discontinued support for Python 3.6, 3.7, and 3.8. Adopted
new Python features from Python versions 3.7-3.9:
- Updated type annotations to use built-in container types
instead of names imported from the `typing` module
(e.g., `list[str]` vs `List[str]`).
- Reworked portions of the packrat cache to leverage
insertion-preserving ordering in dicts (including removal of
uses of `OrderedDict`).
- Changed `pdb.set_trace()` call in `ParserElement.set_break()`
to `breakpoint()`.
- Converted `typing.NamedTuple` to `dataclasses.dataclass`
in railroad diagramming code.
- Added `from __future__ import annotations` to clean up
some type annotations.