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

========

https://hg.mozilla.org/integration/gaia-central/rev/7dd5b4f4e635
Author: Chris Lord <chrislord.net@gmail.com>
Desc: Merge pull request #22121 from Cwiiis/bug-1041383-swipe-notifications

Bug 1041383 - Allow notifications to be dismissed with a leftward swipe. r=mhenretty

========

https://hg.mozilla.org/integration/gaia-central/rev/646b18f0ff57
Author: Chris Lord <chrislord.net@gmail.com>
Desc: Bug 1041383 - Allow notifications to be dismissed with a leftward swipe. r=mhenretty
Bumping manifests a=b2g-bump