feat: fetch languages.json from the GH repository

[Nanush7]

The WST won't need to deploy the compiler to PyPI every time we want to change the languages.json file. The file will be fetched from GitHub (main branch), from https://raw.githubusercontent.com/thewca/wca-regulations-compiler/main/wrc/data/languages.json.

Considerations:

• I wasn't sure whether to use the requests library (which I have used before) or the built-in urllib.requests library. I chose the latter because it's built-in and works perfectly fine for what we need.
• Redirects are handled by urllib automatically. Do we have any issues with allowing redirects?
• The fallback file will be used only if urllib raises HTTPError (e.g. 4xx HTTP errors) or URLError (e.g. on timeout), but not if the fetched JSON cannot be parsed. In that case, the execution will be aborted when trying to parse the contents of the response. I'm doing it like this because getting an invalid JSON from the repo would be a significant issue that should be checked. I can also make it use the fallback in this case if required.

Edit: I'll bump the version in a different PR.