Bumping gaia.json for 1 gaia-central revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/ca8a474b40f9
Author: Eric O'Connor <eric@bocoup.com>
Desc: Bug 934722 - [clock] Unit tests compute timezone offset incorrectly - r=gnarf

Closes gh-13366