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

========

https://hg.mozilla.org/integration/gaia-central/rev/9d61e93e680c
Author: Guillaume C. Marty <edo999@gmail.com>
Desc: Merge pull request #21439 from gmarty/use-css-calc

Use calc() in CSS for more precise styling

========

https://hg.mozilla.org/integration/gaia-central/rev/dd11a1d13082
Author: Guillaume Marty <edo999@gmail.com>
Desc: Use calc() in CSS for more precise styling
Bumping manifests a=b2g-bump