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

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https://hg.mozilla.org/integration/gaia-central/rev/8acca712933d
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Merge pull request #15955 from Rik/inactive-group-after-finishing-call-966951

Bug 966951 - "Group Call" is inactive when received call is hung up r=etienne

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https://hg.mozilla.org/integration/gaia-central/rev/57c4fd44c1dc
Author: Anthony Ricaud <anthony@ricaud.me>
Desc: Bug 966951 - "Group Call" is inactive when received call is hung up

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "c563e12f6af948e050bae885846974db084a187e", 
+    "revision": "8acca712933d58f92f89006afac250ca2ba0797b", 
     "repo_path": "/integration/gaia-central"
 }