insufficient material for position with two bishops of the same color and two kings

[gahtan-syarif]

this position is a draw by insufficient material as both bishops are on the same color, cutechess correctly marked the position as a draw but fast-chess did not

[Disservin]

ah missed that when initially writing this, wikipedia is missing this case https://en.wikipedia.org/wiki/Draw_(chess)#:~:text=insufficient%20material%20to%20checkmate%20include%3A

just needs another check here

https://github.com/Disservin/chess-library/blob/master/src/board.hpp#L658