Update git submodules
- Update skins/MonoBook from branch 'REL1_39' to 098d30eeda911dd9126199166822bc171f0a6578
- build: Update MediaWiki requirement to 1.39.0
Change-Id: Ic2023be7ce8d6b89c31f73223014df7c87bfb395
- build: Update MediaWiki requirement to 1.39.0