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

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https://hg.mozilla.org/integration/gaia-central/rev/c6e222c3d864
Author: Sam Foster <sam@sam-i-am.com>
Desc: Merge pull request #23011 from sfoster/bug-1047143-active-app

Bug 1047143 - close aps entering task-manager, exitToApp to open/restore. r=alive

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https://hg.mozilla.org/integration/gaia-central/rev/be857a20c625
Author: Sam Foster <sfoster@mozilla.com>
Desc: Bug 1047143 - close aps entering task-manager, exitToApp to open/restore

* Fix assumption that home event means homescreen opens in SoundManager,
* Remove appwillopen handler in AttentionScreen, applaunch will suffice

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "ac125ca91aec0f6fd13443a5b41e42a3e837fdcf", 
+    "revision": "c6e222c3d86410830558dcf89436313b431da418", 
     "repo_path": "/integration/gaia-central"
 }