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

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https://hg.mozilla.org/integration/gaia-central/rev/a4457febf5c1
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #14973 from KevinGrandon/bug_953293_search_render_app_like_together

Bug 953293 - [Search] App-like results should be rendered together r=amirn

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https://hg.mozilla.org/integration/gaia-central/rev/17602eb976d2
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 953293 - [Search] App-like results should be rendered together r=amirn