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

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https://hg.mozilla.org/integration/gaia-central/rev/632e0427d2eb
Author: Marcus Cavanaugh <m@mcav.com>
Desc: Merge pull request #17715 from mcav/recompress

Bug 988869 - [Clock] Compress 2.25x image assets. r=jrburke

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https://hg.mozilla.org/integration/gaia-central/rev/b1b1e7290899
Author: Marcus Cavanaugh <m@mcav.com>
Desc: Bug 988869 - [Clock] Compress 2.25x image assets. r=jrburke
Bumping manifests a=b2g-bump