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

========

https://hg.mozilla.org/integration/gaia-central/rev/b29773bd9ae9
Author: Yura Zenevich <yura.zenevich@gmail.com>
Desc: Merge pull request #25503 from yzen/bug-1087592

Bug 1087592 - handling intermittent StaleElementException in calendar se...

========

https://hg.mozilla.org/integration/gaia-central/rev/eb29423c9143
Author: Yura Zenevich <yzenevich@mozilla.com>
Desc: Bug 1087592 - handling intermittent StaleElementException in calendar settings a11y test. r=mmedeiros
Bumping manifests a=b2g-bump