Update git submodules
Update git submodules

* Update plugins/webhooks from branch 'master'
  to 570dacacc64f7c01e0bc0f1301aa1d5a218cfc1b
  - Bazel: Remove unused java_library import
    
    Change-Id: I27e3ea944b55296058ba41cd184078b26f854225
    
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