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

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https://hg.mozilla.org/integration/gaia-2_1/rev/fdcf75e22a1d
Author: Julien Wajsberg <felash@gmail.com>
Desc: Merge pull request #25063 from julienw/1081684-load-default-theme-when-a-theme-is-requested

a=npotb
Bug 1081684 - [Build] Themes don't load when running in Firefox r=ricky
(cherry picked from commit 2543927ea3bfa7ec23d4e9241f62c157e6b128d1)
Bumping manifests a=b2g-bump