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

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https://hg.mozilla.org/integration/gaia-central/rev/823616f0af83
Author: Zac <zcampbell@mozilla.com>
Desc: Merge pull request #16612 from AndreiH/bug_974935

Bug 974935 - Intermittent test_homescreen_delete_app | test_homescreen_l...

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https://hg.mozilla.org/integration/gaia-central/rev/cbc5aa2e1d4f
Author: Andrei Hutusoru <andreihutusoru@P5069.(none)>
Desc: Bug 974935 - Intermittent test_homescreen_delete_app | test_homescreen_launch_app

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https://hg.mozilla.org/integration/gaia-central/rev/aae48dfa9e67
Author: Borja Salguero <borjasalguero@users.noreply.github.com>
Desc: Merge pull request #16289 from borjasalguero/fix_sms

Bug 962328 - [B2G][SMS] The keyboard does not automatically appear when composing a new SMS r=schung

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https://hg.mozilla.org/integration/gaia-central/rev/c970a5922ec1
Author: borjasalguero <fbsc@tid.es>
Desc: Bug 962328 - [SMS] The keyboard does not automatically appear when composing a new SMS r=schung

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "9f96af5a6624a48406a7ef4540266c6480868da3", 
+    "revision": "823616f0af83eca32bceb0367a7a221f8b187110", 
     "repo_path": "/integration/gaia-central"
 }