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

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https://hg.mozilla.org/integration/gaia-central/rev/bd9026211e7c
Author: Evelyn Eastmond <evhan55@gmail.com>
Desc: Bug 936645 - [Messages][Drafts] Add banner message for saved draf r=rwaldron
Bumping manifests a=b2g-bump