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

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https://hg.mozilla.org/integration/gaia-central/rev/67dced59adbe
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Merge pull request #21920 from etiennesegonzac/bug-1037261-complete

Bug 1037261 - Soft home key should not span the bottom of screen in landscape r=etienne

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https://hg.mozilla.org/integration/gaia-central/rev/a953f444d1e7
Author: Markus Nilsson <markus.nilsson@sonymobile.com>
Desc: Bug 1037261 - Soft home key should not span the bottom of screen in landscape
Bumping manifests a=b2g-bump