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

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https://hg.mozilla.org/integration/gaia-2_0/rev/b73e6c7c994a
Author: Fabrice Desré <fabrice@desre.org>
Desc: Merge pull request #21723 from ngokevin/1011016v2.0

Bug 1011016; new marketplace dev/stage packages

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https://hg.mozilla.org/integration/gaia-2_0/rev/5afcfc8d08d4
Author: Kevin Ngo <ngoke@mozilla.com>
Desc: Bug 1011016; new marketplace dev/stage packages
Bumping manifests a=b2g-bump