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

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https://hg.mozilla.org/integration/gaia-central/rev/ef9dc3d0b44f
Author: AndreiH <andrei.hutusoru@softvision.ro>
Desc: Merge pull request #16571 from zacc/bug_976063

Bug 976063 - Python - make wait_*_not run faster

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https://hg.mozilla.org/integration/gaia-central/rev/3775e4a1c848
Author: Zac Campbell <zcampbell@mozilla.com>
Desc: Bug 976063 - Python - make wait_*_not run faster
Bumping manifests a=b2g-bump