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

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https://hg.mozilla.org/integration/gaia-1_4/rev/a3ac54821e29
Author: Michael Henretty <michael.henretty@gmail.com>
Desc: Merge pull request #21488 from shufang-xu/bug1033889xsf_master

 Bug 1033889 - unable to read cell broadcast message on lock screen. r=ferjmoreno,Michael Henretty
Bumping manifests a=b2g-bump