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

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https://hg.mozilla.org/integration/gaia-central/rev/2d20953fd97b
Author: Aleh Zasypkin <aleh.zasypkin@gmail.com>
Desc: Merge pull request #22315 from azasypkin/bug-1046248-attach-button-size

Bug 1046248 - [Messages] Set explicit background image size for "Add attachment" button. r=schung

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https://hg.mozilla.org/integration/gaia-central/rev/f70a14767456
Author: Aleh Zasypkin <azasypkin@mozilla.com>
Desc: Bug 1046248 - [Messages] Set explicit background image size for "Add attachment" button. r=schung

b2g/config/gaia.json

@@ -4,6 +4,6 @@
         "remote": "", 
         "branch": ""
     }, 
-    "revision": "2574260b751962982a91c7a50fbf68d8c7eabc9e", 
+    "revision": "2d20953fd97b5df7e2450ef558b9eeb9962ca1b4", 
     "repo_path": "/integration/gaia-central"
 }