Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_4/rev/766505b57842
Author: Gabriele Svelto <gsvelto@mozilla.com>
Desc: Bug 1051841 - Remove uses of the unavailable 'mmi-notification-title-with-sim' string r=etienne
Bumping manifests a=b2g-bump