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

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https://hg.mozilla.org/integration/gaia-central/rev/c30897e8c63c
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Merge pull request #11993 from arcturus/bug-894872

Bug 911086 - [CONTACTS] Export to Media option should only be active if there is a Media card in the device

========

https://hg.mozilla.org/integration/gaia-central/rev/cea3f000bbeb
Author: Francisco Jordano <arcturus@ardeenelinfierno.com>
Desc: Bug 911086 - [CONTACTS] Export to Media option should only be active if there is a Media card in the device

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "290d2aaaa650f342644a55bfbaead06e1b899107", 
+    "revision": "c30897e8c63c45806ce94f0d7ea0493222cb114d", 
     "repo_path": "/integration/gaia-central"
 }