S8 Max Pooling operator

PiperOrigin-RevId: 391059037
diff --git a/src/operator-strings.c b/src/operator-strings.c
index 8f92ce1..fcab61d 100644
--- a/src/operator-strings.c
+++ b/src/operator-strings.c
@@ -106,6 +106,8 @@
       return "Leaky ReLU (NC, QU8)";
     case xnn_operator_type_max_pooling_nhwc_f32:
       return "Max Pooling (NHWC, F32)";
+    case xnn_operator_type_max_pooling_nhwc_s8:
+      return "Max Pooling (NHWC, S8)";
     case xnn_operator_type_max_pooling_nhwc_u8:
       return "Max Pooling (NHWC, U8)";
     case xnn_operator_type_maximum_nd_f32: