CircleCI has updated its webhook format[1] for CircleCI Cloud,
Server version 3.x and 4.x. This commit rewrites the CircleCI
integration to parse the new webhook structure. The tests have also
been rewritten for the new format.
With this commit, we support webhooks from projects that use GitHub,
BitBucket and GitLab as VCS providers. The CircleCI integration doc
has been updated to mention the same. The doc has also been updated
with the latest instructions for configuring a webhook on the CircleCI
interface, and the new output screenshots.
References:
[1]: https://circleci.com/docs/webhooks