fix fp16 for skiplayernorm (microsoft#20381)

Author: guschmue

js/web/lib/wasm/jsep/webgpu/ops/skip-layer-norm.ts

@@ -136,7 +136,7 @@ const createSkipLayerNormProgramInfo =
         var squareSum = ${fillVector('f32', components)};
         for (var i: u32 = 0; i < hidden_size_vectorized; i++) {
           let skip_value = skip[offset + i];
-          let bias_value = ${hasBiasInput ? 'bias[i]' : '0.0'};
+          let bias_value = ${hasBiasInput ? 'bias[i]' : dataType + '(0.0)'};
           let input_value = x[offset + i];
           let value = input_value + skip_value + bias_value;
           ${hasInputSkipBiasSumOutput ? 'input_skip_bias_sum[offset + i] = value;' : ''}