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

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https://hg.mozilla.org/integration/gaia-central/rev/84dc3d8c2e46
Author: Jim Porter <jporter@mozilla.com>
Desc: Merge pull request #25856 from jimporter/ringtones-rtl

Bug 1094450 - Support RTL for ringtones

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https://hg.mozilla.org/integration/gaia-central/rev/e219610aa3ce
Author: Jim <jporter@mozilla.com>
Desc: Bug 1094450 - Support RTL for ringtones
Bumping manifests a=b2g-bump