Change using pserve-script.py instead of pserve.exe

[Nicknk]

Fix #737

This pull request:

• Has a title summarizes what is changing
• Includes a news entry file (remember to thank yourself!)
• Has unit tests & code coverage is not adversely affected (within reason)
• Works on all actively maintained versions of Python (e.g. Python 2.7 & the latest Python 3 release)
• Works on Windows 10, macOS, and Linux (e.g. considered file system case-sensitivity)

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[DonJayamanne]

@Nicknk
Thanks for the PR, unfortunately I won't be able to accept this PR as I've started working on a fix for it. The solution is also slightly different and better.