Update git submodules

* Update requirements from branch 'master'
  to efffcd29d4d59a953e99963c402cbe956018d4ec
  - Merge "Block prettytable 3.4.0"
  - Block prettytable 3.4.0
    
    That release contains a formatting change that causes nova tests to
    fail[0]. The change has been reverted [1], so using 3.4.1 instead works
    fine.
    
    [0] https://bugs.launchpad.net/nova/+bug/1988482
    [1] jazzband/prettytable#183
    
    Change-Id: I979320cef3ed8c8bee75061b4fcb4c1323cc83a9