Update CDN API class default base_url

[vp-regular]

It looks like https://bunnycdn.com/api/billing was removed, as the endpoint returns 404's instead of 401 when no access key is provided. Current bunnycdn api documentation suggests the current production api endpoint was moved to https://api.bunny.net/ ~two weeks ago. Overriding base_url manually after creating a CDN object seems to return correct billing data.

I smoke tested a couple of the other methods via curl/browser and they seem to point to valid api endpoints, but I didn't test their corresponding methods in this library. This should probably be further tested before merging.

[NiveditJain]

Hey @vp-regular,
Wanted to check for:
1 - Have you tested this URL change?
2 - Please fix this lint issue

[NiveditJain]

or probably we should take the URL as a param from the user, and have a default URL

[vp-regular]

See 289a7b2. Does this repo not use black for formatting? It looks like the linting was already an issue and not part of the diff.

I tested this URL change for CDN.Billing(), not the other functions. See original comment:

I smoke tested a couple of the other methods via curl/browser and they seem to point to valid api endpoints, but I didn't test their corresponding methods in this library. This should probably be further tested before merging.