Update git submodules

* Update system/iot/attestation from branch 'master'
  to 60ada2757857805990b4fd6f69475a19fcdeaa77
  - Add default code reviewers into OWNERS
    
    Bug: 33166666
    Test: gerrit uploader
    Change-Id: I587e9dca1359d68b5cc9058068838b3ec1f30e0b
    
diff --git a/system/iot/attestation b/system/iot/attestation
index cb1f540..60ada27 160000
--- a/system/iot/attestation
+++ b/system/iot/attestation
@@ -1 +1 @@
-Subproject commit cb1f5404c8d217dba3d73a39ae8d19e069da07cc
+Subproject commit 60ada2757857805990b4fd6f69475a19fcdeaa77