Update git submodules

* Update Wikibase from branch 'master'
  to a8b1ff65c1ec4b8e324db51e971774ed728b16ab
  - Merge "Drop compatibility with older data-values versions"
  - Drop compatibility with older data-values versions
    
    To simplify some of our tests again.
    
    Bug: T301249
    Change-Id: Ie9d1655bfb372a7bd80e984f78b86e2fc50404bc
    Depends-On: I86ca22434884ede1a826959bd1e95542bec56a07

Author: jenkins-bot