Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/28f76943ab7f
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #22495 from hobinjk/system-update-ready-prompt-battery

Bug 1042463 - System Update prompt persists in low-battery environment

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https://hg.mozilla.org/integration/gaia-central/rev/711f26caeb05
Author: James Hobin <jhobin@mozilla.com>
Desc: Bug 1042463 - System Update prompt persists in low-battery environment

Fix prompt appearing even when battery is below allowed threshold,
introducing a new update-prompt-result event type.

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https://hg.mozilla.org/integration/gaia-central/rev/477c08dbf0c1
Author: Ryan VanderMeulen <rvandermeulen@mozilla.com>
Desc: Merge pull request #22672 from mozfreddyb/dev-permissions

Bug 1049371 - verbose permissions for developers (first prototype)

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https://hg.mozilla.org/integration/gaia-central/rev/6089d44310b9
Author: Frederik B <fbraun+gh@mozilla.com>
Desc: Bug 1049371 - verbose apps permissions, r=arthurcc
Bumping manifests a=b2g-bump