Fix the advanced pawn evaluation

[programarivm]

The advanced pawn evaluation in src/Eval/AdvancedPawnEval.php needs to be fixed.

Buggy explanation:

• Black has a small advanced pawn advantage.
• Black has a small far advanced pawn advantage.

Buggy elaboration:

• a2 is an advanced pawn.
• a2 is threatening to promote.

A pawn cannot be an advanced pawn and a far advanced pawn at the same time, otherwise as a result the explanation will get too redundant. Thus, a far advanced pawn is also an advanced pawn, however an advanced pawn is not a far advanced pawn.

Fixed explanation:

• Black has a small far advanced pawn advantage.

Fixed elaboration:

• a2 is threatening to promote.