Fix os detection

See rapid7#4283

Author: wchen-r7

modules/exploits/windows/browser/ie_setmousecapture_uaf.rb

@@ -54,10 +54,9 @@ def initialize(info={})
       'BrowserRequirements' =>
         {
           :source    => /script/i,
-          :os_name   => OperatingSystems::WINDOWS,
+          :os_name   => 'Windows 7',
           :ua_name   => HttpClients::IE,
           :ua_ver    => "9.0",
-          :os_flavor => "7",
           :office    => /2007|2010/
         },
       'Targets'        =>