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

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https://hg.mozilla.org/integration/gaia-central/rev/aeb4607cac59
Author: James Burke <jrburke@gmail.com>
Desc: Merge pull request #22937 from jrburke/bug1043527-email-show-external-styling

Bug 1043527 - email UI: Show External Images styling r=asuth

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https://hg.mozilla.org/integration/gaia-central/rev/dda1c29e201b
Author: jrburke <jrburke@gmail.com>
Desc: Bug 1043527 - email UI: Show External Images styling
Bumping manifests a=b2g-bump