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

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https://hg.mozilla.org/integration/gaia-central/rev/d512ea25e7b1
Author: Carsten Book <tomcat@mozilla.com>
Desc: Merge pull request #22621 from mancas/bug796428

Bug 796428 - [Quick Settings] Toggling Mobile data while roaming and Dat... r=kgrandon

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https://hg.mozilla.org/integration/gaia-central/rev/665c75de4b05
Author: Manuel Casas Barrado <manuel.casasbarrado@telefonica.com>
Desc: Bug 796428 - [Quick Settings] Toggling Mobile data while roaming and Data Roaming turned Off
Bumping manifests a=b2g-bump