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

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https://hg.mozilla.org/integration/gaia-central/rev/6a0d87b27463
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #15976 from RudyLu/keyboard/Bug963377-keyboard_covers_value_selector

Bug 963377 - [B2G][Keyboard] Keyboard blocks "cancel" / "ok" options, r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/3ad652828eba
Author: Rudy Lu <me@rudy.lu>
Desc: Bug 963377 - [B2G][Keyboard] Keyboard blocks "cancel" / "ok" options
 - Still reset keyboard state when the keyboard frame is hidden, so that
   the keyboard won't be triggered by the keyboard app after it has
   been dismissed.
Bumping manifests a=b2g-bump