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

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https://hg.mozilla.org/integration/gaia-central/rev/c5ac47192766
Author: Jared Hirsch <ohai@6a68.net>
Desc: Merge pull request #18614 from 6a68/bug-988080-update-fxa-fte-post-signup-copy

Bug 988080 - Update copy for FxA FTE post-signup screen

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https://hg.mozilla.org/integration/gaia-central/rev/1326a5853078
Author: Jared Hirsch <ohai@6a68.net>
Desc: Bug 988080 - Update copy for FxA FTE post-signup screen r=arcturus
Bumping manifests a=b2g-bump