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

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https://hg.mozilla.org/integration/gaia-central/rev/3718511b5780
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Merge pull request #18977 from timdream/value-picker-touch

Bug 1004714 - Use touch events for value pickers, r=rudyl

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https://hg.mozilla.org/integration/gaia-central/rev/70e9f86e1096
Author: Timothy Guan-tin Chien <timdream@gmail.com>
Desc: Bug 1004714 - Use touch events for value pickers
Bumping manifests a=b2g-bump