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

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https://hg.mozilla.org/integration/gaia-central/rev/fab92321f729
Author: Diego Marcos <diego.marcos@gmail.com>
Desc: Merge pull request #15472 from dmarcos/bug961070

Bug 961070 - [Camera] Addressing code comments after bug 959890 merge

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https://hg.mozilla.org/integration/gaia-central/rev/5c89849105f0
Author: Diego Marcos <diego.marcos@gmail.com>
Desc: Bug 961070 - [Camera] Addressing code comments after bug 959890 merge
Bumping manifests a=b2g-bump