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

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https://hg.mozilla.org/integration/gaia-central/rev/c6d486c8faba
Author: Gareth Aye <gaye@mozilla.com>
Desc: Merge pull request #18333 from millermedeiros/980448-modify-account-closing-tag

Bug 980448 - modify-account section missing closing tag r=gaye

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https://hg.mozilla.org/integration/gaia-central/rev/383de1340ff2
Author: Miller Medeiros <miller@millermedeiros.com>
Desc: Bug 980448 - modify-account section missing closing tag
Bumping manifests a=b2g-bump