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

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https://hg.mozilla.org/integration/gaia-central/rev/2a664cbb4d73
Author: marta <marta@sec.t-labs.tu-berlin.de>
Desc: Bug 1083953 - Privacy Panel r=etienne r=ejchen r=timdream r=gandalf
Bumping manifests a=b2g-bump