Update serialization library submodule

Signed-off-by: Eric Kunze <eric.kunze@arm.com>
Change-Id: I82c356681e66bf08e2c106358deb4acbc64a67c8
diff --git a/examples/test_conv2d_1x1_1x32x32x8_f32_st11_padSAME_dilat11/model.pb b/examples/test_conv2d_1x1_1x32x32x8_f32_st11_padSAME_dilat11/model.pb
index 3cddba7..e8c4536 100644
--- a/examples/test_conv2d_1x1_1x32x32x8_f32_st11_padSAME_dilat11/model.pb
+++ b/examples/test_conv2d_1x1_1x32x32x8_f32_st11_padSAME_dilat11/model.pb
@@ -137,5 +137,5 @@
   }
 }
 versions {
-  producer: 1286
+  producer: 1387
 }