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

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https://hg.mozilla.org/integration/gaia-central/rev/a4f204058209
Author: James Lal <james@lightsofapollo.com>
Desc: Merge pull request #11551 from KevinGrandon/bug_817564_remove_day_label

Bug 817564 - Remove day header label

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https://hg.mozilla.org/integration/gaia-central/rev/913973b11d58
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 817564 - Remove day header label