Yubihsm

** NOTE: Backwards incompatible release.
** Dropped Python 2 support, new minimum requirement: Python 3.8.
** Added type hints.
** Bumped minimum supported Cryptography version to 2.6.
** Dropped yubihsm.eddsa package, in favor of EdDSA support in Cryptography.
** Dropped custom constants for Brainpool curves, in favor of those in Cryptography.
** Dropped `.generated`, `.imported`, and `.wrapped` from ORIGIN.
Instead use: `ORIGIN.GENERATED in origin`, etc.
** Added support for asymmetric authentication.
** Added support for symmetric encryption (AES).
** Changes relevant to maintainers:
*** Added mypy to pre-commit checks.
*** Switched build and packaging system to poetry.
*** Switched to using pytest for testing (unittest still used in some places).
*** Dependency fix: Generating documentation with Sphinx requires Python >= 3.8.

** Bugfix: Fix broken sign_ssh_certificate command.

** Dependency fix: Require Cryptography <38.

** Stop using deprecated functions from cryptography.io (prevents warnings).
** Support Prehashed data when signing.
** Implement context manager (python with-statement) for YubiHsm and AuthSession.
** Bugfix: Fix byte-order issue with AEAD nonce ID.

** Bugfix: ORIGIN representation was broken, causing get_info() to fail.
** Bugfix: Algorithm parsing in DeviceInfo fixed.
** Handing of too large messages improved.

** Published under the Apache v2.0 software license.
** Reworked most library APIs to align with SDK 2.0 changes.
** Added documentation to all public APIs, with Sphinx generated docs.