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

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https://hg.mozilla.org/integration/gaia-central/rev/c437654b4dc4
Author: steveck-chung <schung@mozilla.com>
Desc: Merge pull request #14295 from steveck-chung/bug-944869

Bug 944869 - Improve English in message error alerts. r=julienw

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https://hg.mozilla.org/integration/gaia-central/rev/8147f5d20984
Author: Steve Chung <schung@mozilla.com>
Desc: Bug 944869 - Improve English in message error alerts