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

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https://hg.mozilla.org/integration/gaia-central/rev/a944e0010f4b
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Merge pull request #13921 from dominickuo/bug-936397

Bug 936397 - [music2] Implement the current views with tablet style - part 1, r=jimporter

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https://hg.mozilla.org/integration/gaia-central/rev/d7647f0822d0
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Bug 936397 - [music2] Implement the current views with tablet style - part 1