Update py3.

test/test_lexer.py

@@ -1,10 +1,10 @@
 """
 Unit tests for the lexer.
 """
-from StringIO import StringIO
 from tempfile import NamedTemporaryFile
 import unittest
 
+from six import StringIO
 
 from lesscpy.lessc.lexer import LessLexer
 

test/test_parser.py

@@ -1,11 +1,13 @@
 """
 Unit test for the parser.
 """
-from StringIO import StringIO
 import unittest
 
+from six import StringIO
+
 from lesscpy.lessc.parser import LessParser
 
+
 class TestLessParser(unittest.TestCase):
     """
     Unit tests for LessParser.