Unihan-etl

Development

- Move to `src/`-layout structure (266)
- Add [flake8-bugbear](https://github.com/PyCQA/flake8-bugbear) (#263)
- Add [flake8-comprehensions](https://github.com/adamchainz/flake8-comprehensions) (#264)

Documentation

- Render changelog in [`linkify_issues`] (~~261~~, 265)
- Fix Table of contents rendering with sphinx autodoc with [`sphinx_toctree_autodoc_fix`] (265)
- Test doctests in our docs via [`pytest_doctest_docutils`] (built on [`doctest_docutils`]) (265)

[`linkify_issues`]: https://gp-libs.git-pull.com/linkify_issues/
[`sphinx_toctree_autodoc_fix`]: https://gp-libs.git-pull.com/sphinx_toctree_autodoc_fix/
[`pytest_doctest_docutils`]: https://gp-libs.git-pull.com/doctest/pytest.html
[`doctest_docutils`]: https://gp-libs.git-pull.com/doctest

Documentation

- Add vendorized, updated fork of `sphinxcontrib-issuetracker`, via 261.
- Remove sphinx-issues package

Follow ups to 257.

Fixes

- `merged_dict()`: Fix merging edgecase where destination key was missing
- `download()`: Fix edgecase when "downloading" file from local path

Features

- mypy `--strict` annotations, via 257

Features

- New option: `--no-cache`

Disregard cached .zip / extracted files, via 259.

Development

- Add python 3.8 and 3.9 to CI

This is to make way for strict type annotations, as the typings and generic
behavior vary dramatically between 3.7 - 3.11.

Breaking changes

- Python 2 compatibility module and imports removed. Python 2.x was officially
dropped in 0.12.0 (2021-06-15) via 258