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

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https://hg.mozilla.org/integration/gaia-1_4/rev/2d8493f05da8
Author: Rudy Lu <me@rudy.lu>
Desc: Merge pull request #17870 from RudyLu/keyboard/Bug959200_master

Bug 959200 - Letters on keyboard sometimes not placed correctly.
r=janjongboom(cherry picked from commit b68b9f9a266727ed8fee3b6664c4316393caab8e)
a=1.3t+, bajaj
Bumping manifests a=b2g-bump