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

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https://hg.mozilla.org/integration/gaia-central/rev/6c139b2c645b
Author: evanxd <itoyxd@gmail.com>
Desc: Merge pull request #16435 from evanxd/bug-973876

Bug 973876 - make test-integration shouldn't ask for admin password

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https://hg.mozilla.org/integration/gaia-central/rev/4b4f3cdd35f5
Author: Evan Xd <itoyxd@gmail.com>
Desc: Bug 973876 - Remove the admin permission request.
Bumping manifests a=b2g-bump