Bumping gaia.json for 1 gaia revision(s) a=gaia-bump

========

https://hg.mozilla.org/integration/gaia-2_1/rev/051564fece56
Author: Guillaume C. Marty <gmarty@users.noreply.github.com>
Desc: Merge pull request #26297 from gmarty/Bug-1095142-Dialer-screen-does-not-fully-cover-lockscreen a=bajaj

Bug 1095142 - [SHB] Dialer screen does not fully cover lockscreen
Conflicts:
	apps/system/js/attention_window_manager.js
	apps/system/js/layout_manager.js
	apps/system/test/unit/layout_manager_test.js
Bumping manifests a=b2g-bump