Update PSReadLine to 2.2.0-beta4 for idle handler support

Author: rjmholt

modules.json

@@ -6,6 +6,7 @@
         "Version": "1.1.3"
     },
     "PSReadLine": {
-        "Version": "2.1.0"
+        "Version": "2.2.0-beta4",
+        "AllowPrerelease": true
     }
 }