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

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https://hg.mozilla.org/integration/gaia-central/rev/3a3c79436baa
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #16781 from viorelaioia/bug_978099

Bug 978099 - Better wait in test_video_empty.TestVideoEmpty

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https://hg.mozilla.org/integration/gaia-central/rev/f10812ad3ca8
Author: Viorela Ioia <viorelaioia@gmail.com>
Desc: Bug 978099 - Better wait in test_video_empty.TestVideoEmpty
Bumping manifests a=b2g-bump