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

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https://hg.mozilla.org/integration/gaia-central/rev/b0a272695ccf
Author: steveck-chung <schung@mozilla.com>
Desc: Merge pull request #23773 from steveck-chung/bug-983172-planB

Bug 983172 - Parsing jpeg header information for downsampling the image for thumbnail. r=azasypkin

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https://hg.mozilla.org/integration/gaia-central/rev/a7ffeb643354
Author: Steve Chung <schung@mozilla.com>
Desc: Bug 983172 - Parsing jpeg header information for downsampling the image for thumbnail, r=azasypkin
Bumping manifests a=b2g-bump