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

========

https://hg.mozilla.org/integration/gaia-central/rev/5ce93b34e9c9
Author: Wilson Page <wilsonpage@me.com>
Desc: Merge pull request #25327 from wilsonpage/1073489

Bug 1073489 - [gaia-header] the back icon needs to be swapped in RTL documents

========

https://hg.mozilla.org/integration/gaia-central/rev/d49bc7c8c3bf
Author: Wilson Page <wilsonpage@me.com>
Desc: Bug 1073489 - [gaia-header] the back icon needs to be swapped in RTL documents
Bumping manifests a=b2g-bump