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

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https://hg.mozilla.org/integration/gaia-central/rev/d7d077bcbd42
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Merge pull request #16167 from dominickuo/bug-968456

Bug 968456 - [Music] Put Music App Behind a Scrollable Layer, r=dominickuo

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https://hg.mozilla.org/integration/gaia-central/rev/8be10cd10bef
Author: Mason Chang <mchang@mozilla.com>
Desc: Bug 968456 - [Music] Put Music App Behind a Scrollable Layer
Bumping manifests a=b2g-bump