0.5.10

Improve typing to make mypy pass and activate mypy on CI (#135)

* refactor: move `importlib.metadata` import to `compat`
* build(deps): add `types-chardet`
* build(deps): bump `mypy` to `0.981`
* chore(mypy): use proper booleans for config
* chore(mypy): explicitly set files to run on
* chore(tox): enable mypy
* chore: improve typing