Pawn does not promote when reaching the other end

[Nickvanhurck]

When the pawn reaches the other end of the board the pawn does not promote.

[CZSeas]

if (player == WHITE and _to[0] == 7) or (player == BLACK and _to[0] == 0):

should be changed to

if (player == WHITE and _to[0] == 0) or (player == BLACK and _to[0] == 7):

[scoldi]

It should be noted that a pawn can promote to any of the pieces (except king or another pawn, obviously), not just a queen. So the options are queen, rook, knight or bishop.

The current implementations of both v1 and v2 seem to only support promotion to a queen:
new_state[_to[0], _to[1]] = QUEEN_ID * self.player_to_int(player)