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

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https://hg.mozilla.org/integration/gaia-central/rev/f446053df7cc
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #23008 from KevinGrandon/bug_1052503_system_progress_bar

Bug 1052503 - [Rocketbar] Update loading progress bar

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https://hg.mozilla.org/integration/gaia-central/rev/76b7bd1e82c9
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1052503 - [Rocketbar] Update loading progress bar r=benfrancis
Bumping manifests a=b2g-bump