Bumping gaia.json for 1 gaia-1_2 revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-1_2/rev/3f92117abbe5
Author: Dominic Kuo <dkuo@mozilla.com>
Desc: Merge pull request #14251 from dominickuo/bug-943797

Bug 943797 - [music] Use hash to decide the default album art, r=jimporter(cherry picked from commit e01827ec7b9bc0426e0f5d216123b9247413db4e)