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

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https://hg.mozilla.org/integration/gaia-central/rev/3163ba4cfcfa
Author: Rex KM Lee <rexboy@mozilla.com>
Desc: Merge pull request #12494 from rexboy7/fix-bug898376

Bug 898376 - [Contacts] Fix error handling on importing contact

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https://hg.mozilla.org/integration/gaia-central/rev/e5c0edae113c
Author: Rex Lee <rexboy@mozilla.com>
Desc: Bug 898376 - [Contacts] Fix error handling on importing contact