Update git submodules

Update git submodules

* Update docs/submodules/functest from branch 'master'
  - Update Xtesting to 0.54.0

    It protects vs uncaught exceptions and then avoids skipping testcases
    in that case (see cloudify_ims and juju_epc in [1]).

    [1] https://build.opnfv.org/ci/view/functest/job/functest-apex-baremetal-daily-master/188/console

    Change-Id: I8e39f7e742b9fec2e6f6bab542d5f497159f50ac
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>
  - Delete alt images before removing the account

    Else it could raise unauthorized exceptions [1].

    [1] https://build.opnfv.org/ci/view/functest/job/functest-apex-baremetal-daily-master/188/console

    Change-Id: Ia9b857069f775e2c8ecc5e07cf39b3a1fb7e3540
    Signed-off-by: Cédric Ollivier <cedric.ollivier@orange.com>