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

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https://hg.mozilla.org/integration/gaia-2_1/rev/7579d83aece1
Author: Justin D'Arcangelo <justindarc@gmail.com>
Desc: Merge pull request #25636 from justindarc/bug1079543-v2.1

Bug 1079543 - Preview is getting freeze after opening & closing Camera a...

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https://hg.mozilla.org/integration/gaia-2_1/rev/d3b2c1a9f2e1
Author: Justin D'Arcangelo <justindarc@gmail.com>
Desc: Bug 1079543 - Preview is getting freeze after opening & closing Camera app during WEBRTC video call
Bumping manifests a=b2g-bump