3.0.0

What's Changed

• Add Python 3.10 & Python 3.11 support. See #51.
• Drop Python 2.7 support. It's dead for more than a year anyway. Those who want to use picobox with Python 2 should stick with 2.x branch. See #39.
• Drop Python 3.4, Python 3.5 and Python 3.6 support. They reached their end-of-life and are not maintained anymore. See #39 and #52.
• Add type annotations to public interface. Now users can use mypy to leverage type checking in their code base. See #47.
• Make some parameters keyword-only: factory and scope in Box.put(), as_ in Box.pass_() and chain in picobox.push(). See #49.
• Use PEP 621 pyproject.toml in a so-called source distribution.

Full Changelog: 2.2.0...3.0.0