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

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https://hg.mozilla.org/integration/gaia-central/rev/648ac7e58497
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #17184 from KevinGrandon/bug_983568_search_marketaplce_api_endpoint

Bug 983568 - [Search] Implement new lightweight Marketplace API r=eperelman

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https://hg.mozilla.org/integration/gaia-central/rev/e44be2a3a9db
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 983568 - [Search] Implement new lightweight Marketplace API r=eperelman
Bumping manifests a=b2g-bump