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

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https://hg.mozilla.org/integration/gaia-central/rev/56f2c5c5906b
Author: Zac <zcampbell@mozilla.com>
Desc: Revert "Xfail Bug 1000863 - Investigate test_fmradio_find_stations.py failure"

This reverts commit e37e1f1744cc325b326ba8975e66082d0915ef30.
Bumping manifests a=b2g-bump