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

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https://hg.mozilla.org/integration/gaia-central/rev/c387a7eb0eef
Author: Arnau <arnau@arnaumarch.com>
Desc: Merge pull request #18018 from rnowm/992771

Bug 992771 - [VRD][Homescreen] use new Buttons and Inputs [BB] r=crdlc

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https://hg.mozilla.org/integration/gaia-central/rev/9639783ee0f3
Author: rnowm <arnau@arnaumarch.com>
Desc: Bug 992771 - [VRD][Homescreen] use new Buttons and Inputs [BB]
Bumping manifests a=b2g-bump