Update app.py

[gapilongo]

• Modularization: The code is broken down into functions, which improves readability and makes the code easier to maintain.
• Error Handling: Adds a print statement in the fetch_stock_data function to notify the user when a stock's data cannot be loaded.
• Variable Naming: msft is renamed to ticker to make it clear that it can represent any stock ticker, not just Microsoft.

These changes aim to make the code more robust, easier to read, and the output more professional.

[Berat-O]

These changes sound like they're really going to enhance the codebase. Modularization and proper error handling are crucial for maintainability and reliability. Renaming msft to ticker also makes the code more understandable and flexible.Thank you for your contribution! Your improvements have been merged into the codebase. The changes you've made greatly enhance the readability and robustness of the code, which is invaluable to our project.