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

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https://hg.mozilla.org/integration/gaia-central/rev/979add320adb
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Merge pull request #13116 from mcjimenez/bug928134

Bug 928134 - When powering on a device for the first time with a SIM customization variant with app preloads, an app install success notification unexpectedly appears r=etienne

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https://hg.mozilla.org/integration/gaia-central/rev/3e4e6a58ce16
Author: Carmen Jimenez Cabezas <cjc@tid.es>
Desc: Bug 928134 - When powering on a device for the first time with a SIM customization variant with app preloads, an app install success notification unexpectedly appears