Update git submodules

Update git submodules

* Update docs/submodules/ccsdk/platform/plugins.git from branch 'master'
  to 8e573aa799c96cbe2a0404e58d67f48eea50b9db
  - Merge "Make pgaas tests propagate test failures"
  - Make pgaas tests propagate test failures

    Reraise the exceptions so that test harness reports them properly.
    Fix parameters passed in test_update_database.
    Ensure strings are encoded before hashing (enforced in python3).

    Signed-off-by: Miroslav Los <miroslav.los@pantheon.tech>
    Issue-ID: CCSDK-1929
    Change-Id: Iee098fd53bc0fbd1c69d737002d1f63f9548f7f4