py3: use print as a function in tests/test-hgweb.t

Differential Revision: https://phab.mercurial-scm.org/D4461

tests/test-hgweb.t

@@ -329,7 +329,7 b' stop and restart'
 
 Test the access/error files are opened in append mode
 
-  $ $PYTHON -c "print len(open('access.log', 'rb').readlines()), 'log lines written'"
+  $ $PYTHON -c "from __future__ import print_function; print(len(open('access.log', 'rb').readlines()), 'log lines written')"
   14 log lines written
 
 static file