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

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https://hg.mozilla.org/integration/gaia-central/rev/d8c297cc7df5
Author: vingtetun <21@vingtetun.org>
Desc: Merge pull request #23988 from etiennesegonzac/bug-1061324-followup-followup

Bug 1061324 Follow follow up - Making the whole task_manager_test suite ...

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https://hg.mozilla.org/integration/gaia-central/rev/d69437d6d9e8
Author: Etienne Segonzac <etienne@segonzac.info>
Desc: Bug 1061324 Follow follow up - Making the whole task_manager_test suite use fakeTimers.

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "ea8c68de5506cc37143e2670dd09d0a8ee9b87e4", 
+    "revision": "d8c297cc7df5f8c4876d634c170f8b2cbd9d38af", 
     "repo_path": "/integration/gaia-central"
 }