Added

• Support for h5py version 3 (#411).
• Added pyupgrade to pre-commit hooks (#413).
• Code is formatted with black and isort pre-commit hooks (#415).
• Added macOS to CircleCI testing pipeline (#281, #414).
• Official support for Python 3.9 (#417).

Changed

• Optimized internal function _mkdir_p (#421).
• Optimized performance of job initialization (#422).
• Optimized performance of buffer storage (#428).
• Optimized performance of creating/loading synced data structures (#429).