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

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https://hg.mozilla.org/integration/gaia-central/rev/52ce9e518c8e
Author: Rudy Lu <me@rudy.lu>
Desc: Merge pull request #18151 from RudyLu/keyboard/Bug956182-new_layouts

Bug 956182 - [keyboard refactor] convert layout files to new format.
r=timdream

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https://hg.mozilla.org/integration/gaia-central/rev/8239c9253562
Author: Rudy Lu <me@rudy.lu>
Desc: Bug 956182 - [keyboard refactor] convert layout files to new format.
Bumping manifests a=b2g-bump