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

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https://hg.mozilla.org/integration/gaia-central/rev/afc73def64af
Author: Jonathan Griffin <jgriffin@mozilla.com>
Desc: Merge pull request #11099 from jonallengriffin/coupling

Bug 895697 - Add a pointer to gaia-ui-tests, r=aki, a=test-only

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https://hg.mozilla.org/integration/gaia-central/rev/f5ebc90805a0
Author: Jonathan Griffin <jgriffin@mozilla.com>
Desc: Bug 895697 - Add a pointer to gaia-ui-tests, r=aki, a=test-only