[utils] remove useless u prefix

youtube_dl/utils.py

@@ -131,7 +131,7 @@ if sys.version_info >= (2, 7):
         """ Find the xpath xpath[@key=val] """
         assert re.match(r'^[a-zA-Z-]+$', key)
         assert re.match(r'^[a-zA-Z0-9@\s:._-]*$', val)
-        expr = xpath + u"[@%s='%s']" % (key, val)
+        expr = xpath + "[@%s='%s']" % (key, val)
         return node.find(expr)
 else:
     def find_xpath_attr(node, xpath, key, val):