python-chess v1.9.1

Bugfixes:

* Reject pawn capture SAN if the original file is not specified, e.g.,
  ``d5`` will no longer match ``cxd5``.

Changes:

* Tweak handling of whitespace in PGN comments: When parsing, any leading
  and trailing whitespace (beyond one space) is preserved. When joining
  multiple PGN comments, they are now separated with a space instead of a
  newline character. When removing annotations from comments, leftover
  whitespace is avoided.

New features:

* Add model ``sf15`` for ``chess.engine.Score.wdl()``.