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

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https://hg.mozilla.org/integration/gaia-central/rev/3a9f9c152429
Author: John Hu <johu@mozilla.com>
Desc: Merge pull request #25641 from huchengtw-moz/bug-1090810-use-settings-cache

Bug 1090810 - [Stingray] add SettingsCache to smart system, r=rexboy

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https://hg.mozilla.org/integration/gaia-central/rev/8a2f39fc25d8
Author: John Hu <johu@mozilla.com>
Desc: Bug 1090810 - [Stingray] add SettingsCache to smart system
Bumping manifests a=b2g-bump