Python 3.6 invalid escape sequence deprecation fixes

_pytest/pytester.py

@@ -332,7 +332,7 @@ def testdir(request, tmpdir_factory):
     return Testdir(request, tmpdir_factory)
 
 
-rex_outcome = re.compile("(\d+) ([\w-]+)")
+rex_outcome = re.compile(r"(\d+) ([\w-]+)")
 class RunResult:
     """The result of running a command.
 

_pytest/tmpdir.py

@@ -116,7 +116,7 @@ def tmpdir(request, tmpdir_factory):
     path object.
     """
     name = request.node.name
-    name = re.sub("[\W]", "_", name)
+    name = re.sub(r"[\W]", "_", name)
     MAXVAL = 30
     if len(name) > MAXVAL:
         name = name[:MAXVAL]