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

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https://hg.mozilla.org/integration/gaia-1_3/rev/ff7e002a5a2e
Author: Marcus Cavanaugh <m@mcav.com>
Desc: Revert "Revert "Bug 986753 - [Tarako] Alarm Clock can get killed in the background and never ring." for suspicion of breaking gaia integration tests"

This reverts commit a968d8cd00fa1f370a2ea7e3994b5bb5391affd7.
Bumping manifests a=b2g-bump