[Feature Request] Add concurrency with proxies

[phoenixpereira]

Overview

Add concurrency with proxies for the scraper.

Details

• Fetch a list of proxies and save working ones to a text file.
• Use the working proxies with concurrency to scrape course data.
• Add retry logic after getting a 429 error to try other proxies before waiting for 60 seconds.

Why would this feature be useful?

This will significantly reduce the scraping time and allow automated daily scraping to happen on GitHub actions, thus allowing support for how full a class currently is.

Additional Notes

No response