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

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https://hg.mozilla.org/integration/gaia-central/rev/c247e5387c54
Author: Arthur Chen <crh0716@gmail.com>
Desc: Merge pull request #26314 from crh0716/1099374_master

Bug 1099374 - Add the target attribute to links r=eragonj

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https://hg.mozilla.org/integration/gaia-central/rev/6eb829809e9c
Author: Arthur Chen <crh0716@gmail.com>
Desc: Bug 1099374 - Add the target attribute to links
Bumping manifests a=b2g-bump