Bumping gaia.json for 2 gaia revision(s) a=gaia-bump

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https://hg.mozilla.org/integration/gaia-central/rev/fb36e8999d3f
Author: Carmen Jiménez <cjc@tid.es>
Desc: Merge pull request #19691 from mcjimenez/bug1006172

Bug 1006172 - Use Homescreen configuration file and process SingleVariant apps

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https://hg.mozilla.org/integration/gaia-central/rev/fe096443dd2f
Author: Carmen Jimenez Cabezas <cjc@tid.es>
Desc: Bug 1006172 - Use Homescreen configuration file and process SingleVariant apps
Bumping manifests a=b2g-bump