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

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https://hg.mozilla.org/integration/gaia-1_4/rev/acf1ec23829a
Author: Justin D'Arcangelo <justindarc@gmail.com>
Desc: Merge pull request #18379 from justindarc/bug996513

Bug 996513 - [Flame][Camera] front camera can not work in master branch
Bumping manifests a=b2g-bump