Use escapes for some regex expressions.

parso/grammar.py

@@ -134,7 +134,7 @@ class Grammar(object):
 
 
 def _parse_version(version):
-    match = re.match('(\d+)(?:\.(\d)(?:\.\d+)?)?$', version)
+    match = re.match(r'(\d+)(?:\.(\d)(?:\.\d+)?)?$', version)
     if match is None:
         raise ValueError('The given version is not in the right format. '
                          'Use something like "3.2" or "3".')

parso/utils.py

@@ -83,5 +83,5 @@ def version_info():
     """
     Version = namedtuple('Version', 'major, minor, micro')
     from parso import __version__
-    tupl = re.findall('[a-z]+|\d+', __version__)
+    tupl = re.findall(r'[a-z]+|\d+', __version__)
     return Version(*[x if i == 3 else int(x) for i, x in enumerate(tupl)])