Removed redundant 'import cgi' from normalize.py

Author: phillmv

test/normalize.py

@@ -14,7 +14,6 @@ class HTMLParseError(Exception):
 from html.entities import name2codepoint
 import sys
 import re
-import cgi
 
 # Normalization code, adapted from
 # https://github.com/karlcow/markdown-testsuite/