build(ci): add new headers to changelog, change label names

[AnonymousWP]

Describe the feature you want

At the moment the changelog is very cluttered, also because we assign different labels to the header 'Miscellaneous'. We should add the following headers:

• Highlights
• Development
• Documentation

'Miscellaneous' is kept for for other minor stuff. I also want to rename the testing label to ci.

Acknowledgements

• This issue is not a duplicate of an existing feature request.
• I have chosen an appropriate title.
• All requested information has been provided properly.