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
    
1 file changed