Bumping gaia.json for 2 gaia-central revision(s)

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https://hg.mozilla.org/integration/gaia-central/rev/9b3ffbd7fe9f
Author: evanxd <itoyxd@gmail.com>
Desc: Merge pull request #10970 from evanxd/bug-893694

Bug 893694 - [Calendar] Update the 1.5x version of images for Calendar App

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https://hg.mozilla.org/integration/gaia-central/rev/3b60d2882d1b
Author: Evan Xd <itoyxd@gmail.com>
Desc: Bug 893694 - Update the 1.5x version of images.

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "911756823e4537d9be0df3b18634398f2a41e39c", 
+    "revision": "9b3ffbd7fe9f5d6ccee5b1ac7866f5fdfe6e5b10", 
     "repo_path": "/integration/gaia-central"
 }