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

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https://hg.mozilla.org/integration/gaia-2_0/rev/8c20be89ebe9
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 1020959 - [vertical] search bar is visible when geolocation prompt is present r=alive
Bumping manifests a=b2g-bump