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

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https://hg.mozilla.org/integration/gaia-central/rev/cb3ab98cbc87
Author: Arnau <arnau@arnaumarch.com>
Desc: Merge pull request #17851 from rnowm/990528

Bug 990528 - [Messaging][Visual refresh][Regression] Adding several recipients breaks the layout r=bfrancis

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https://hg.mozilla.org/integration/gaia-central/rev/c1281d4712ba
Author: rnowm <arnau@arnaumarch.com>
Desc: Bug 990528 - [Messaging][Visual refresh][Regression] Adding several recipients breaks the layout
Bumping manifests a=b2g-bump