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

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https://hg.mozilla.org/integration/gaia-central/rev/04255cf60df6
Author: Carsten Book -Tomcat- <cbook@mozilla.com>
Desc: Revert "Bug 897352 - [gaia build system] Transition to a build_stage for assembling apps" for Breaking Windows Builds

This reverts commit 91c8fd2a33c9be6a745a3f30a6e5113831655502.
Bumping manifests a=b2g-bump