python-chess v0.22.2

Bugfixes:

* In standard chess promoted pieces were incorrectly considered as
  distinguishable from normal pieces with regard to position equality
  and threefold repetition. Thanks to kn-sq-tb for reporting.

Changes:

* The PGN `game.headers` are now a custom mutable mapping that validates the
  validity of tag names.
* Basic attack and pin methods moved to `BaseBoard`.
* Documentation fixes and improvements.

New features:

* Added `Board.lan()` for long algebraic notation.