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

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https://hg.mozilla.org/integration/gaia-central/rev/67e048984f96
Author: No-Jun Park <npark@mozilla.com>
Desc: Merge pull request #30496 from npark-mozilla/1172624

Bug 1172624 - Convert python marionette test_gallery_empty.py script to marionettejs test empty_image_test.js

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https://hg.mozilla.org/integration/gaia-central/rev/a2db19bde9d3
Author: No-Jun Park <npark@mozilla.com>
Desc: Bug 1172624 - Convert python marionette test_gallery_empty.py script to marionettejs test

b2g/config/gaia.json

@@ -1,9 +1,9 @@
 {
     "git": {
-        "git_revision": "fb7e0cec2aefbd1b2a90af3af17b0036915db0b3", 
+        "git_revision": "8efb95e8d217e4718301cfb26e2f9aa5165cb0c4", 
         "remote": "https://git.mozilla.org/releases/gaia.git", 
         "branch": ""
     }, 
-    "revision": "517f0073f5f7b2f688898d30cc479e597224f846", 
+    "revision": "67e048984f96ac8072fd782b350463c546f5a52b", 
     "repo_path": "integration/gaia-central"
 }