[pyatspi2] Python 3.6 invalid escape sequence deprecation fix

[Mike Gorse <mgorse src gnome org>]

commit 63c8a0d6cce954bedae34a7f6ebc5807fbef0c14
Author: Ville Skyttä <ville skytta iki fi>
Date:   Tue Mar 14 13:35:51 2017 +0200

    Python 3.6 invalid escape sequence deprecation fix
    
    https://docs.python.org/3/whatsnew/3.6.html#deprecated-python-behavior

 pyatspi/utils.py |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/pyatspi/utils.py b/pyatspi/utils.py
index c7a5705..da1f3fc 100644
--- a/pyatspi/utils.py
+++ b/pyatspi/utils.py
@@ -339,7 +339,7 @@ def attributeListToHash(list):
         ret = dict()
         for item in list:
                 [key, val] = item.split(":")
-                val = val.replace(":", "\:")
+                val = val.replace(":", r"\:")
                 if ret.__contains__(key):
                     ret[key] = ret[key] + ":" + val
                 else: