Fix rapid7#9215, minor style nitpick

Author: wvu

modules/exploits/multi/http/drupal_drupageddon.rb

@@ -474,12 +474,12 @@ def exploit_newuser
 
   def exploit
     case datastore['TARGET']
-      when 0
-        exploit_formcache
-      when 1
-        exploit_newuser
-      else
-        fail_with(Failure::BadConfig, "Invalid target selected.")
+    when 0
+      exploit_formcache
+    when 1
+      exploit_newuser
+    else
+      fail_with(Failure::BadConfig, "Invalid target selected.")
     end
   end
 end