Update git submodules
Update git submodules

* Update scripts/i18n from branch 'master'
  to 7238a6b984b172d7537239713947ebd8cb12548d
  - [tests] Use Python 3.6 instead of 3.4 for tests
    
    Use default Python which is 3.6.7 currently
    to hide FutureWarning about deprecated Python version.
    
    Change-Id: Ie94277e2e8824bb284465cffe2654a90276d3847
    
wikimedia/pywikibot-core,wikimedia/pywikibot-core,PersianWikipedia/pywikibot-core