Refactored currencies.py to handle currency logic only

[sue-lim]

Refactored currencies.py to Isolate Currency Logic

[FEATURE] Currency Script | Create a currency management module #432

Summary

Separated currency-specific logic into currencies.py for modularity and easier maintenance.

Description

This PR introduces improvements by modularising the project. The changes focus on extracting currency-related functionality into its own module, currencies.py, which includes functions for:

• Getting supported currency codes
• Validating if a currency is supported

The changes are as follows:

• Created currencies.py module
• Added get_supported_currencies() function
• Added is_valid_currency() function
• Included manual test examples in the main block
• Improved readability and beginner-friendliness of code
• Removed unnecessary type hints for simplicity

Checks

in the repository

• Made no changes that degrades the functioning of the repository
• Gave each commit a better title (unlike updated README.md)

in the PR

• Followed the format of the pull_request_template
• Made the Pull Request in a small level (for the creator's wellfare)
• Tested the changes you made, manually & via unittest

Thank You,

Sue

[sue-lim]

@DhanushNehru - please kindly approve PR.