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

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https://hg.mozilla.org/integration/gaia-central/rev/da576217a863
Author: Sam Joch <samuel@guiora.com>
Desc: Merge pull request #10580 from pivanov/bug-885925

Bug 885925 - Header in the calendar sidebar is different from the header in the building block r=@samjoch

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https://hg.mozilla.org/integration/gaia-central/rev/52a95db5f38b
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 885925 - Header in the calendar sidebar is different from the header in the building block