Fix bad scaling of last layer's bias

Non-regression STC:
LLR:  2.94/2.94<-6.00, 0.00> Elo diff: 0.22 [-2.42, 2.87] (95%)
Games: 17238 W: 2319 L: 2306 D: 12613 Draw ratio: 73.2%
Pntl: [148, 1640, 5033, 1647, 150]

Non-regression LTC:
LLR:  2.94/2.94<-6.00, 0.00> Elo diff: 2.50 [-0.97, 5.96] (95%)
Games: 6544 W: 593 L: 546 D: 5405 Draw ratio: 82.6%
Pntl: [19, 449, 2294, 486, 24]

Bench: 1902101

src/NNUE.cpp

@@ -147,7 +147,7 @@ namespace NNUE
 
     Score Accumulator::eval(const Accumulator& stm, const Accumulator& ntm, int bucket)
     {
-        int output = nnue_net->m_dense_bias[bucket];
+        int output = nnue_net->m_dense_bias[bucket] * SCALE_FACTOR;
         for (std::size_t i = 0; i < NUM_ACCUMULATORS; i++)
         {
             // Clipped ReLU on the accumulators