bpo-19696: Replace deprecated method in "test_import_pkg.py" (GH-14466)

Replacing the deprecated method "random.choose" to "random.choice" was technically not part of the original issue. However, it was discussed in the talk page and involved one of the files being moved. I assumed this was too minor to justify the creation of a separate issue. 

Also, I added my name to the contributors list in Misc/ACKS. This will be my third PR to cpython, forgot to do it in the previous ones. 



https://bugs.python.org/issue19696