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

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https://hg.mozilla.org/integration/gaia-central/rev/6680a4aa31f0
Author: Arnau <arnau@arnaumarch.com>
Desc: Merge pull request #19083 from rnowm/948856

Bug 948856 - [Settings] Update setting icons to use Icon Fonts r=arthurcc

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https://hg.mozilla.org/integration/gaia-central/rev/eeb7849bcf86
Author: rnowm <arnau@arnaumarch.com>
Desc: Bug 948856 - [Settings] Update setting icons to use Icon Fonts
Bumping manifests a=b2g-bump