docs: fix simple typo, raies -> raise (stefankoegl#135)

Author: timgates42

ext_tests.py

@@ -65,7 +65,7 @@ def _test(self, test):
                 raise Exception(test.get('comment', '')) from jpe
 
             # if there is no 'expected' we only verify that applying the patch
-            # does not raies an exception
+            # does not raise an exception
             if 'expected' in test:
                 self.assertEquals(res, test['expected'], test.get('comment', ''))