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

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https://hg.mozilla.org/integration/gaia-central/rev/890c4574edd4
Author: John Hu <johu@mozilla.com>
Desc: Merge pull request #26276 from huchengtw-moz/bug-1101375-home-transparent-bg

Bug 1101375 - [Stingray][home] change background to transparent, r=dwi2

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https://hg.mozilla.org/integration/gaia-central/rev/5aea885ab83d
Author: John Hu <johu@mozilla.com>
Desc: Bug 1101375 - [Stingray][home] change background to transparent
Bumping manifests a=b2g-bump