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

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https://hg.mozilla.org/integration/gaia-central/rev/586bbefdaeef
Author: Teodosia Pop <teodosia.pop@gmail.com>
Desc: Merge pull request #13668 from bobsilverberg/tbpl_up

Bug 934446 - Test Messages contact input validation

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https://hg.mozilla.org/integration/gaia-central/rev/37c8cec676a6
Author: Bob Silverberg <bob.silverberg@gmail.com>
Desc: Bug 934446 - Test Messages contact input validation