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

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https://hg.mozilla.org/integration/gaia-central/rev/123eb4378d29
Author: Yura Zenevich <yura.zenevich@gmail.com>
Desc: Merge pull request #24018 from yzen/bug-1066793

Bug 1066793 - improved ambient notification indicator accessibility.

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https://hg.mozilla.org/integration/gaia-central/rev/07b79e535484
Author: Yura Zenevich <yzenevich@mozilla.com>
Desc: Bug 1066793 - improved ambient notification indicator accessibility. r=alive
Bumping manifests a=b2g-bump