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

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https://hg.mozilla.org/integration/gaia-central/rev/5d6a52354620
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #16628 from 6a68/bug-972645-reset-password

Bug 972645 - Implement Reset Password Firefox Accounts flow

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https://hg.mozilla.org/integration/gaia-central/rev/6b4bfac91fae
Author: Jared Hirsch <ohai@6a68.net>
Desc: Bug 972645 - Implement Reset Password Firefox Accounts flow. r=ferjm

  Includes special case for reset password in FTE, see bug 965494 comment 1
Bumping manifests a=b2g-bump