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

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https://hg.mozilla.org/integration/gaia-central/rev/56a86e2dc7c3
Author: Yura Zenevich <yura.zenevich@gmail.com>
Desc: Merge pull request #23156 from yzen/bug-1030351

Bug 1030351 - screen is hidden from the screen reader until either the s...

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https://hg.mozilla.org/integration/gaia-central/rev/03473dab226f
Author: Yura Zenevich <yzenevich@mozilla.com>
Desc: Bug 1030351 - screen is hidden from the screen reader until either the splash or the logo are hidden. r=alive, francisco
Bumping manifests a=b2g-bump