update ruby example

Co-authored-by: Nick Rolfe <[email protected]>

Author: erik-krogh

ruby/ql/src/queries/security/cwe-116/examples/BadTagFilter.rb

@@ -1,8 +1,8 @@
-def filterScripTags(html)
-  oldHtml = "";
-  while (html != oldHtml)
-    oldHtml = html;
-    html = html.gsub(/<script[^>]*>.*<\/script>/m, "");
+def filter_script_tags(html)
+  old_html = ""
+  while (html != old_html)
+    old_html = html
+    html = html.gsub(/<script[^>]*>.*<\/script>/m, "")
   end
-  return html;
+  html
 end