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

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https://hg.mozilla.org/integration/gaia-central/rev/616f677c56b0
Author: John Hu <johu@mozilla.com>
Desc: Merge pull request #25822 from huchengtw-moz/bug-1092934-settings-app

Bug 1092934 - [Stingray] Create settings app for changing landing app, r=dwi2

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https://hg.mozilla.org/integration/gaia-central/rev/253cbf14774e
Author: John Hu <johu@mozilla.com>
Desc: Bug 1092934 - [Stingray] Create settings app for changing landing app
Bumping manifests a=b2g-bump