Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/bf0e846f93b0
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Merge pull request #17228 from dominickuo/bug-958470-new

Bug 958470 - [Ringtones] set ringer type and use web audio api to preview the ringtones, r=jimporter

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https://hg.mozilla.org/integration/gaia-central/rev/c378a9e41a95
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Bug 958470 - [Ringtones] set ringer type and use web audio api to preview the ringtones
Bumping manifests a=b2g-bump