Update Atmosphere to fix reconnect problem (#18686)

Change-Id: I0c2825c8f4c6f44eb16c9106aaac7e0add6e1a5f

push/ivy.xml

@@ -3,7 +3,7 @@
 <!-- Keep the version number in sync with build.xml -->
     <!ENTITY atmosphere.runtime.version "2.2.7.vaadin1">
 
-    <!ENTITY atmosphere.js.version "2.2.6.vaadin4">
+    <!ENTITY atmosphere.js.version "2.2.6.vaadin5">
 ]>
 <ivy-module version="2.0"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"