add delete_dirs function (Sourcery refactored)

[sourcery-ai]

Pull Request #58 refactored by Sourcery.

Since the original Pull Request was opened as a fork in a contributor's
repository, we are unable to create a Pull Request branching from it.

To incorporate these changes, you can either:

1. Merge this Pull Request instead of the original, or

2. Ask your contributor to locally incorporate these commits and push them to
   the original Pull Request

   Incorporate changes via command line

   git fetch https://github.com/ultralytics/JSON2YOLO pull/58/head
   git merge --ff-only FETCH_HEAD
   git push

NOTE: As code is pushed to the original Pull Request, Sourcery will
re-run and update (force-push) this Pull Request with new refactorings as
necessary. If Sourcery finds no refactorings at any point, this Pull Request
will be closed automatically.

See our documentation here.

Run Sourcery locally

Reduce the feedback loop during development by using the Sourcery editor plugin:

• VS Code
• PyCharm

Help us improve this pull request!

🛠️ PR Summary

_{Made with ❤️ by Ultralytics Actions}

📊 Key Changes

• A delete_dirs function is added to utils.py to remove specific file types from directories.
• The make_dirs function now uses delete_dirs instead of shutil.rmtree for directory deletion.
• Updated the way shell commands are executed in flatten_recursive_folders function by using f-strings.
• Simplified representation of the coco91_to_coco80_class function's return array for better readability.

🎯 Purpose & Impact

• The new delete_dirs function provides a safer way to delete files by targeting specific file extensions, potentially reducing the risk of unintended data loss 💥.
• New implementations using f-strings make code cleaner and more maintainable. This modern python syntax improves the readability of shell command execution 🧾.
• No impact on user-facing features is expected, but developers can enjoy a cleaner and more maintainable codebase ✨.

🌟 Summary

Refactored codebase including a new directory deletion function and improved syntax for script commands 🧹.