Bumping gaia.json for 1 gaia-central revision(s)

========

https://hg.mozilla.org/integration/gaia-central/rev/44b5d39b37b1
Author: Eitan Isaacson <eitan@monotonous.org>
Desc: Bug 914886 - [Settings] Use aria-disabled instead of disabled class. r=kaze

Relanding after linter error resolved.

b2g/config/gaia.json

@@ -1,4 +1,4 @@
 {
-    "revision": "21d0f4126507812091b99a3d2c8a142d3d3e32a3", 
+    "revision": "44b5d39b37b1e0e07e09953f52d176f687f15018", 
     "repo_path": "/integration/gaia-central"
 }