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

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https://hg.mozilla.org/integration/gaia-central/rev/925ab0b53ca2
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Revert "Bug 958470 - [Ringtones] set ringer type and use web audio api to preview the ringtones"

This reverts commit 4b6b7d119563bb6554c6b49d7f3ad6a2092261f8.
Bumping manifests a=b2g-bump