Bumping gaia.json for 3 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/38a1fd737228
Author: steveck-chung <schung@mozilla.com>
Desc: Merge pull request #14539 from steveck-chung/message-timestamp-changes

Bug 944881 - Gaia should interpret timestamps as long-long numbers. r=julienw, a=blocking-b2g 1.3+

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https://hg.mozilla.org/integration/gaia-central/rev/1190eb0646f1
Author: Steve Chung <schung@mozilla.com>
Desc: Utilize Date.now() and other fixing.

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https://hg.mozilla.org/integration/gaia-central/rev/aa7004ea3513
Author: Steve Chung <schung@mozilla.com>
Desc: Bug 944881 - Gaia should interpret timestamps as long-long numbers