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

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https://hg.mozilla.org/integration/gaia-central/rev/60c37ec919c7
Author: Zac <zcampbell@mozilla.com>
Desc: Revert "Revert "Bug 924833 - Re-enable test_receive_call.py" for requiring plivo, which isn't on the mirror"

This reverts commit 381009095bc7d2b9aea26a641f5e8df7c8728efc.
Bumping manifests a=b2g-bump