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

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https://hg.mozilla.org/integration/gaia-central/rev/7cce6db8e564
Author: John Hu <johu@mozilla.com>
Desc: Merge pull request #18566 from huchengtw-moz/video/Bug_998263-wrong-file-size

Bug 998263 - [Tarako][Gallery][Video]Image/Video file size is incorrect, r=djf, r=alive

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https://hg.mozilla.org/integration/gaia-central/rev/08821cd5f445
Author: John Hu <johu@mozilla.com>
Desc: Bug 998263 - [Tarako][Gallery][Video]Image/Video file size is incorrect
Bumping manifests a=b2g-bump