Bumping gaia.json for 4 gaia-central revision(s)

========

https://hg.mozilla.org/integration/gaia-central/rev/7b8f6640e82b
Author: Sam Joch <samuel@guiora.com>
Desc: Merge pull request #11963 from pivanov/bug-912998

Bug 912998 - [Calendar] Fix layout of Add an Account Screen r=samjoch

========

https://hg.mozilla.org/integration/gaia-central/rev/7222781504c1
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 912998 - [Calendar] Fix layout of Add an Account Screen

========

https://hg.mozilla.org/integration/gaia-central/rev/e61b3b21d02b
Author: Sam Joch <samuel@guiora.com>
Desc: Merge pull request #11961 from pivanov/bug-912995

Bug 912995 - [Calendar] Left align text in Calendar dropdowns r=samjoch

========

https://hg.mozilla.org/integration/gaia-central/rev/de675421d833
Author: Pavel Ivanov <pivanov@mozilla.com>
Desc: Bug 912995 - [Calendar] Left align text in Calendar dropdowns