v0.22.0

Fixed

• Removed broken Dependabot badge in README (#377)

Added

• Python 3.10 support (#380)
• __eq__ method for Signature objects (#383)
• unrecognized_fields attribute for Signature objects (#387)

Changed

• Bumped dependencies: cffi (#373), cryptography (#376, #379), ed25519 (#378,
  #390), pycparser (#375), pynacl (#382)
• Misc docstring improvements (#380, #381, #384)

Removed

• Python 3.6 support (#385)