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

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https://hg.mozilla.org/integration/gaia-1_4/rev/13ec9647174a
Author: Fernando Rodríguez Sela <frsela@tid.es>
Desc: Merge pull request #20986 from frsela/STK/Bug1027521

Bug 1027521 - [Sora]Phone returns to wrong screen when trying to return to previous screen in STK menu, r=jaoo
Bumping manifests a=b2g-bump