Bumping gaia.json for 3 gaia-central revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-central/rev/f5ec8e3ab7d2
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Merge pull request #15223 from KevinGrandon/reenable_rocketbar_tests

Reenable rocketbar tests

========

https://hg.mozilla.org/integration/gaia-central/rev/20c778ba3a88
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Run a lot

========

https://hg.mozilla.org/integration/gaia-central/rev/aa8e268457e1
Author: Kevin Grandon <kevingrandon@yahoo.com>
Desc: Re-enable rocketbar tests