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

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https://hg.mozilla.org/integration/gaia-central/rev/3fb4a3797c82
Author: steveck-chung <schung@mozilla.com>
Desc: Merge pull request #17330 from steveck-chung/bug-981401

Bug 981401 - [Messages] Notification does not vanish when the SMS is read when going back from sleep. r=arcturus

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https://hg.mozilla.org/integration/gaia-central/rev/3cd119248490
Author: Steve Chung <schung@mozilla.com>
Desc: Bug 981401 - [Messages] Notification does not vanish when the SMS is read when going back from sleep
Bumping manifests a=b2g-bump