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

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https://hg.mozilla.org/integration/gaia-1_4/rev/6ae5fc6adfa2
Author: Cristian Rodriguez <crdlc@tid.es>
Desc: Merge pull request #18639 from crdlc/bug-1000454

Bug 1000454 - [B2G][1.4][Gaia]: The timestamp for a file downloaded a we...
Bumping manifests a=b2g-bump