Docstrfmt

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**Changed**

- Switch from unmaintained ``appdirs`` to the replacement ``platformdirs``.

**Fixed**

- An issue where the summary line of docstring was incorrectly wrapped.

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**Added**

- Add ``appdirs`` dependency.

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**Added**

- Add Pre-commit hooks.

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**Added**

- Add a check for blank fields and raise an error when found.
- Add ``toml`` dependency.

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**Added**

- Add ability to specify config setting from ``pyproject.toml``.

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**Changed**

- Use click<8.0.0 due to an issue with globbing on Windows.

**Fixed**

- Fix bug where exclude paths were not being excluded properly.