bpo-29693: Fix for DeprecationWarning in test_import (#421)

Patch by Anish Shah.

Lib/test/test_import/__init__.py

@@ -85,7 +85,7 @@ class ImportTests(unittest.TestCase):
             from os import i_dont_exist
         self.assertEqual(cm.exception.name, 'os')
         self.assertEqual(cm.exception.path, os.__file__)
-        self.assertRegex(str(cm.exception), "cannot import name 'i_dont_exist' from 'os' \(.*os.py\)")
+        self.assertRegex(str(cm.exception), r"cannot import name 'i_dont_exist' from 'os' \(.*os.py\)")
 
     def test_from_import_missing_attr_has_name_and_so_path(self):
         import select
@@ -93,7 +93,7 @@ class ImportTests(unittest.TestCase):
             from select import i_dont_exist
         self.assertEqual(cm.exception.name, 'select')
         self.assertEqual(cm.exception.path, select.__file__)
-        self.assertRegex(str(cm.exception), "cannot import name 'i_dont_exist' from 'select' \(.*\.(so|pyd)\)")
+        self.assertRegex(str(cm.exception), r"cannot import name 'i_dont_exist' from 'select' \(.*\.(so|pyd)\)")
 
     def test_from_import_missing_attr_has_name(self):
         with self.assertRaises(ImportError) as cm: