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

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https://hg.mozilla.org/integration/gaia-central/rev/679956ac96e3
Author: gasolin <gasolin@gmail.com>
Desc: Merge pull request #17186 from gasolin/issue-983572

Bug 983572 - [ui-test-privileged ] add gUM video permission in manifest, r=atsai

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https://hg.mozilla.org/integration/gaia-central/rev/e0b92566e231
Author: gasolin <gasolin@gmail.com>
Desc: Bug 983572 - [ui-test-privileged ] add gUM video permission in manifest
Bumping manifests a=b2g-bump