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

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https://hg.mozilla.org/integration/gaia-central/rev/bcfc13353f31
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Bug 989644 - Disable intermittent failing test on travis, Music player tests Audio channels tests Interrupted by a higher priority channel
Bumping manifests a=b2g-bump