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

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https://hg.mozilla.org/integration/gaia-central/rev/b31671ba516a
Author: steveck-chung <schung@mozilla.com>
Desc: Merge pull request #19187 from flodolo/bug1009405

Bug 1009405 - [SMS] Restore data-l10n-id in Send button. r=schung

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https://hg.mozilla.org/integration/gaia-central/rev/6dc85ce07bf7
Author: Francesco Lodolo (:flod) <flod@lodolo.net>
Desc: Bug 1009405 - [SMS] Restore data-l10n-id to Send button
Bumping manifests a=b2g-bump