Update git submodules

Update git submodules

* Update swift from branch 'master'
  to 1698fc32489572787af45cab2bb9b8774ab1fb90
  - OldestAsyncPendingTracker accepts Timestamp.internal

    The OldestAsyncPendingTracker.add_update() method is passed a
    timestamp string which is derived from the name of the async_pending
    file. This string may take the internal form of a Timestamp which
    cannot be directly cast to a float; the string should be cast to a
    Timestamp instance and then cast to a float.

    Change-Id: Ibe48a9193cd0a062cbf629f2ff0d950881380f48
    Signed-off-by: Alistair Coles <alistairncoles@gmail.com>