Add files for Pomodoro timer application

[gh-adithya]

Fix to Issue #133

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A simple pomodoro timer application made using the Python Tkinter module and no other requirements! The time periods can be changed by adjusting relevant values in main.py

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Checklist

• [x] I read the contributing guidelines
• [x] I structured my project as stated in the contributing guidelines
• [x] My project uses dependencies
• [x] I starred the repo
• [x] I had fun contributing!

[theadeyemiolayinka]

Project reviewed and merged. Thank you @gh-adithya Feel free to add more projects.