[doctestutils] Fix some flake8 errors on escape sequence

--HG--
branch : 0.1

cubicweb_jsonschema/doctestutils.py

@@ -52,10 +52,10 @@ def _parse_webtest_testresponse(string):
             break
     else:
         raise ParseError('not a webtest.TestResponse string')
-    if not re.match('Response: \d{3} \w+', status):
+    if not re.match(r'Response: \d{3} \w+', status):
         raise ParseError('not a webtest.TestResponse string')
     headers = []
-    while re.match('[a-zA-Z\-]+: [^\n]+\n', rest):
+    while re.match(r'[a-zA-Z\-]+: [^\n]+\n', rest):
         header, rest = rest.split('\n', 1)
         name, value = header.split(':', 1)
         headers.append((name.strip(), value.strip()))