Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/8b3f177cf138
Author: Julien Wajsberg <felash@gmail.com>
Desc: Revert "Bug 1072856 - [Messages] Tapping on empty space above send and attach buttons should assimilate currently edited recipient. r=julienw"

This reverts commit 1926e9d063b024748e13eb0aa347f18ee57a6cb4.
Bumping manifests a=b2g-bump