Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/db9384dbb7d6
Author: Jonathan Griffin <jgriffin@mozilla.com>
Desc: Merge pull request #16054 from rwood-moz/updatechecker

Bug 965426 - FakeUpdateChecker fails on Tarako devices, r=jgriffin

========

https://hg.mozilla.org/integration/gaia-central/rev/4769480d99fd
Author: rwood-moz <rwood@mozilla.com>
Desc: Bug 965426 - FakeUpdateChecker fails on Tarako devices, r=jgriffin
Bumping manifests a=b2g-bump