Same weight for black and white nonPawnCorrection history

Since we don't have color dependent parameters in NNUE eval, it also has
no sense IMO to have color dependent parameters in correction histories.

Ideally a fixed depth search on a single thread should be determistic,
so delivering the same result (move) if we just flip colors on the
board.

Patch replaces 2 parameters (128 and 150) with just one value 139 (= the avg of the two).

src/search.cpp

@@ -1340,7 +1340,8 @@ Value Search::Worker::search(
         && ((bestValue < ss->staticEval && bestValue < beta)  // negative correction & no fail high
             || (bestValue > ss->staticEval && bestMove)))     // positive correction & no fail low
     {
-        const auto m = (ss - 1)->currentMove;
+        const auto       m             = (ss - 1)->currentMove;
+        static const int nonPawnWeight = 139;
 
         auto bonus = std::clamp(int(bestValue - ss->staticEval) * depth / 8,
                                 -CORRECTION_HISTORY_LIMIT / 4, CORRECTION_HISTORY_LIMIT / 4);
@@ -1349,9 +1350,9 @@ Value Search::Worker::search(
         thisThread->majorPieceCorrectionHistory[us][major_piece_index(pos)] << bonus * 185 / 128;
         thisThread->minorPieceCorrectionHistory[us][minor_piece_index(pos)] << bonus * 101 / 128;
         thisThread->nonPawnCorrectionHistory[WHITE][us][non_pawn_index<WHITE>(pos)]
-          << bonus * 128 / 128;
+          << bonus * nonPawnWeight / 128;
         thisThread->nonPawnCorrectionHistory[BLACK][us][non_pawn_index<BLACK>(pos)]
-          << bonus * 150 / 128;
+          << bonus * nonPawnWeight / 128;
 
         if (m.is_ok())
             (*(ss - 2)->continuationCorrectionHistory)[pos.piece_on(m.to_sq())][m.to_sq()] << bonus;