Added Mastermind game Python mini project code.

[aksvisu]

Description

A python program that stimulates a GUI for the Mastermind game.

Fixes #414

• Adds a new Python mini project.

Type of change

• [ ] Bug fix (non-breaking change which fixes an issue)
• [x] New feature (non-breaking change which adds functionality)
• [ ] Documentation Update

Checklist:

• [x] I have named my files and folder, according to this project's guidelines.
• [x] My code follows the style guidelines of this project.
• [x] My Pull Request has a descriptive title. (not a vague title like Update index.md)
• [x] I have commented on my code, particularly in hard-to-understand areas.
• [x] I have created a helpful and easy to understand README.md, according to the given README_TEMPLATE.
• [x] I have included a requirements.txt file (if external libraries are required.)
• [x] My changes do not produce any warnings.
• [x] I have added a working sample/screenshot of the script.