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

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https://hg.mozilla.org/integration/gaia-central/rev/c448b6769528
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Merge pull request #23604 from pivanov/bug-1059093

Bug 1046336 - (2.1-visual-refresh) System Sound Refresh r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/fdb49c904318
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 1046336 - (2.1-visual-refresh) System Sound Refresh
Bumping manifests a=b2g-bump