Color code output highlighting version parts that changed

Only applies when using `--dry-run`.

For ex, copying ncu:

<img width="461" alt="Screenshot 2023-08-23 at 5 48 40 PM" src="https://github.com/alanhamlett/pip-update-requirements/assets/522344/18f5459a-ac2e-4fd3-a5d9-71eb7f02f47c">
