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

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https://hg.mozilla.org/integration/gaia-central/rev/57f880925125
Author: Carsten Book -Tomcat- <cbook@mozilla.com>
Desc: Revert "Bug 937970 - [Settings] Move 'Sample Format' section below language selector. r=arthurcc" for Breaking Gaia Unit Tests

This reverts commit 50a19f9900fc2a63dd532fb21c82d320a9695f66.