Update serialization library submodule

Signed-off-by: Eric Kunze <eric.kunze@arm.com>
Change-Id: I82c356681e66bf08e2c106358deb4acbc64a67c8
diff --git a/examples/test_add_1x4x4x4_f32/model.pb b/examples/test_add_1x4x4x4_f32/model.pb
index f76ec12..b8db82e 100644
--- a/examples/test_add_1x4x4x4_f32/model.pb
+++ b/examples/test_add_1x4x4x4_f32/model.pb
@@ -92,5 +92,5 @@
   }
 }
 versions {
-  producer: 1286
+  producer: 1387
 }