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

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https://hg.mozilla.org/integration/gaia-central/rev/765148289558
Author: vingtetun <21@vingtetun.org>
Desc: Merge pull request #21751 from vingtetun/rename-brand-to-theme-and-support-new-event

Bug 1038638 - Rename brand-color to theme-color to match spec. r=alive

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https://hg.mozilla.org/integration/gaia-central/rev/42a4c87bb441
Author: Vivien Nicolas <vnicolas@mozilla.com>
Desc: Bug 1038638 - Rename brand-color to theme-color to match spec. r=alive
Bumping manifests a=b2g-bump