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

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https://hg.mozilla.org/integration/gaia-central/rev/31361435df09
Author: Dave Hunt <dave.hunt@gmail.com>
Desc: Bug 1061735 - Post logcat to Treeherder report. r=rwood
Bumping manifests a=b2g-bump