Bumping gaia.json for 2 gaia-1_3 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_3/rev/596a612100b0
Author: GaryChen(pychen) <mmm198219@gmail.com>
Desc: Merge pull request #15239 from mpizza/Bug_957906_v1.3

Bug 957906 - [fugu][buri][settings] cannot backward from keyboard settings. r=rudyl, arthurcc.

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https://hg.mozilla.org/integration/gaia-1_3/rev/9bff08b0a8a4
Author: mpizza <mmm198219@gmail.com>
Desc: Bug 957906 - [fugu][buri][settings] cannot backward from keyboard settings