Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/9676f43f3c4b
Author: German Toro del Valle <gtorodelvalle@gmail.com>
Desc: Revert "Bug 1027471 - [LockScreen][System] Split notification.js into LockScreen and System parts"

This reverts commit 61ab5bf41df531eaee8dcbf2511ddd5608e2e9d7.
Bumping manifests a=b2g-bump