Update transcript in Testing Chapter 5

The word "mark" in the transcripts should be "mock".  Updated the
transcript - found two more instances for update.

Author: prcutler

transcripts/10-testing/5.txt

@@ -17,9 +17,9 @@
 00:54 And for this I'm just going to use the unittest
 00:57 patch method on the mock module
 01:00 because it's a perfect fit for this scenario.
-01:05 So from unittest.mark, import patch.
+01:05 So from unittest.mock, import patch.
 01:10 I actually need to import to random module
-01:12 because that's the one we're going to mark.
+01:12 because that's the one we're going to mock.
 01:15 And you can use it as patch object
 01:20 and that's to random module. Just specify the function
 01:24 or method you want to patch.