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

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https://hg.mozilla.org/integration/gaia-central/rev/73c156ba149b
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #13658 from RudyLu/keyboard/Bug931201-dutch_keyboard_layout

Bug 931201 - Add Dutch keyboard layout, fix some locale-layout mapping, r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/e4a1bbd925e7
Author: Rudy Lu <me@rudy.lu>
Desc: Bug 931201 - Add Dutch keyboard layout.
 - Also clean up some entries in shared/resources/keyboard_layouts.json