One new feature and a deprecation:
* Added the `LongestAlternativeParser` parser and its alias `longest` (21)
* Added `first` as an alias for `AlternativeParser`, which is the parser behind the `|` operator
* **Deprecation warning:** In Parsita 2.0, the `|` operator will use `longest` instead of `first`, and `AlternativeParser` will be renamed to `FirstAlternativeParser`. This is intended to make alternatives more intuitive. `first` and `longest` behave the same in most cases, but users should explicitly switch from `|` to `first` if the current behavior is desired.
A handful of other changes:
* Dropped Python 3.6 support
* Improved documentation and type hints of `Result`
Overhaul of infrastructure and some refactorings to latest Python features (no changes to package behavior):
* Created a [documentation website](https://parsita.drhagen.com/)
* Moved continuous integration from TravisCI to GitHub Actions
* Migrated the build system from setuptools to poetry
* Switched from tox to nox-poetry
* Added black and isort as code quality tools
* Refactored all string type annotations to use `from __future__ import annotations` now that Python 3.6 is gone
* Refactored all `.format` calls to use f-strings now that Python 3.5 is gone