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

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https://hg.mozilla.org/integration/gaia-central/rev/138728dcba2b
Author: Marcus Cavanaugh <m@mcav.com>
Desc: Merge pull request #16228 from mcav/vibrate

Bug 971162 - [B2G][Clock][Alarm] Clock alarm has vibration when alarm vi...

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https://hg.mozilla.org/integration/gaia-central/rev/c6a9aa703125
Author: Marcus Cavanaugh <m@mcav.com>
Desc: Bug 971162 - [B2G][Clock][Alarm] Clock alarm has vibration when alarm vibration is set to off. r=gaye
Bumping manifests a=b2g-bump