Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/30e923643bc1
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #10770 from KevinGrandon/bug_889895_remove_mouse_shim

Bug 889895 - Remove mouse system shim

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https://hg.mozilla.org/integration/gaia-central/rev/3918189e22e4
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 889895 - Remove mouse system shim