Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-2_0/rev/83c6479fbc1b
Author: Zac <zcampbell@mozilla.com>
Desc: Bug 1027144 - Disable test_homescreen_move/delete tests due to bug 1027708 a=testonly
Bumping manifests a=b2g-bump