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

========

https://hg.mozilla.org/integration/gaia-central/rev/c559f121b48c
Author: Arnau <arnau@arnaumarch.com>
Desc: Merge pull request #19584 from rnowm/1015043

Bug 1015043 - Add edit mode behavior to gaia-buttons r=wilsonpage

========

https://hg.mozilla.org/integration/gaia-central/rev/b76e573b8c41
Author: rnowm <arnau@arnaumarch.com>
Desc: Bug 1015043 - Add edit mode behaviour to gaia-buttons
Bumping manifests a=b2g-bump