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

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https://hg.mozilla.org/integration/gaia-central/rev/ec70f92e5f82
Author: Amir Nissim <amirnissim@gmail.com>
Desc: Merge pull request #14918 from EverythingMe/941637-eme-aria

Bug 941637 - App icons don't have alt text so screen readers can't read ...

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https://hg.mozilla.org/integration/gaia-central/rev/3f2a6416d372
Author: Amir Nissim <amirnissim@gmail.com>
Desc: Bug 941637 - App icons don't have alt text so screen readers can't read them [r=ranbena]