Bumping gaia.json for 3 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/56f30855d90b
Author: Dale Harvey <dale@arandomurl.com>
Desc: Bug 1063685 - Fix lookup for browser windows. r=alive

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https://hg.mozilla.org/integration/gaia-central/rev/63462de4a73d
Author: albertopq <albert.pastor@gmail.com>
Desc: Merge pull request #24187 from albertopq/1068659-circle-icon

Bug 1068659 - Resizing no-data icon r=mhenretty

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https://hg.mozilla.org/integration/gaia-central/rev/6ddc318ed89c
Author: albertopq <apastor@mozilla.com>
Desc: Bug 1068659 - Resizing no-data icon
Bumping manifests a=b2g-bump