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

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https://hg.mozilla.org/integration/gaia-2_0/rev/6321ee46a43e
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #22541 from justindarc/bug1044033-v2.0

Bug 1044033 - Video Encode: Flicker in the preview can be observed when ...

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https://hg.mozilla.org/integration/gaia-2_0/rev/b57cbf8e1aee
Author: Justin D'Arcangelo <justindarc@gmail.com>
Desc: Bug 1044033 - Video Encode: Flicker in the preview can be observed when we change the resolution in front camera
Bumping manifests a=b2g-bump