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

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https://hg.mozilla.org/integration/gaia-central/rev/8427d20a1b39
Author: Yoshi Huang <allstars.chh@mozilla.com>
Desc: Merge pull request #18305 from svic/Bug_966921

Bug 966921 - Restore state of BT adapter after a file transfer. r=evelyn

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https://hg.mozilla.org/integration/gaia-central/rev/f573c221baf9
Author: Arno Puder <arno@puder.org>
Desc: Bug 966921 - Restore state of BT adapter after a file transfer
Bumping manifests a=b2g-bump