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

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https://hg.mozilla.org/integration/gaia-central/rev/375197d3c3a9
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Merge pull request #20288 from dominickuo/bug-1015837

Bug 1015837 - [System] Sound toast visual refresh, r= alivedise

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https://hg.mozilla.org/integration/gaia-central/rev/82d3e3ff975b
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Bug 1015837 - [System] Sound toast visual refresh
Bumping manifests a=b2g-bump