Fix flake8 trailing whitespace

Author: nonameentername

html5lib/utils.py

@@ -19,7 +19,7 @@
 # UTF-16 as its encoding of unicode strings, such as Jython. This is
 # because UTF-16 itself is based on the use of such surrogates, and
 # there is no mechanism to further escape such escapes.
-# 
+#
 # Otherwise we assume such support.
 supports_lone_surrogates = platform.python_implementation() != "Jython"