Update PSReadLine in modules.json (#1121)

Author: TylerLeonhardt

modules.json

@@ -10,7 +10,7 @@
         "AllowPrerelease":false
     },
     "PSReadLine":{
-        "MinimumVersion":"2.0.0-beta5",
+        "MinimumVersion":"2.0.0-beta6",
         "MaximumVersion":"2.1",
         "AllowPrerelease":true
     }