Bumping gaia.json for 4 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-2_1/rev/4a721d8e1e05
Author: Doug Sherk <github@sherk.me>
Desc: Bug 1069439 - Fix ICE contacts not showing up on emergency call screen. r=Rik

========

https://hg.mozilla.org/integration/gaia-2_1/rev/ddbd96ee084c
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Bug 1065147 - DTMF volume is reduced significantly and cannot be increased after a call

========

https://hg.mozilla.org/integration/gaia-2_1/rev/145968efd687
Author: Yura Zenevich <yzenevich@mozilla.com>
Desc: Bug 1068202 - fixed cards view statusbar screen reader visibility. Added tests.

Conflicts:
	tests/python/gaia-ui-tests/gaiatest/tests/accessibility/system/manifest.ini

========

https://hg.mozilla.org/integration/gaia-2_1/rev/32af9b729c89
Author: Kyle Machulis <kyle@nonpolynomial.com>
Desc: Bug 1069064 - Fix name of function called to continue migrating bookmarks
Bumping manifests a=b2g-bump