Fix incorrect passing of flags to re.sub

Author: hauntsaninja

feedparser/html.py

@@ -149,7 +149,7 @@ def feed(self, data):
         :rtype: None
         """
 
-        data = re.sub(r'<!((?!DOCTYPE|--|\[))', r'&lt;!\1', data, re.IGNORECASE)
+        data = re.sub(r"<!((?!DOCTYPE|--|\[))", r"&lt;!\1", data, flags=re.IGNORECASE)
         data = re.sub(r'<([^<>\s]+?)\s*/>', self._shorttag_replace, data)
         data = data.replace('&#39;', "'")
         data = data.replace('&#34;', '"')