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

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https://hg.mozilla.org/integration/gaia-central/rev/c94420395a6b
Author: steveck-chung <schung@mozilla.com>
Desc: Merge pull request #12177 from steveck-chung/issue913378

Bug 913378 - Redesign of incoming call screen - Gaia implementation. r=etienne a=koi+

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https://hg.mozilla.org/integration/gaia-central/rev/30be20b5c73e
Author: Steve Chung <schung@mozilla.com>
Desc: Bug 913378 - Redesign of incoming call screen - Gaia implementation