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

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https://hg.mozilla.org/integration/gaia-central/rev/4abeb620f7a1
Author: Jared Hirsch <ohai@6a68.net>
Desc: Merge pull request #20096 from johngruen/bug-1013522-firefox-account-ui-should-match

bug 1013522 firefox account ui should match

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https://hg.mozilla.org/integration/gaia-central/rev/60217bd9de0e
Author: johngruen <john.gruen@gmail.com>
Desc: Bug 1013522 - Firefox Accounts system app visual polish. r=ferjm
Bumping manifests a=b2g-bump