Feature request: log label add/remove in the PR Activity

[AMorgaut]

Some of our PR labels have important meaning in our validation process

• the same way comment and approvals are listed in the PR Activity
• we'd like to be able to track there also when and who added or removed a label

Example:

Activity

• Jane Doe removed the label VF to the pull request 07 Aug 2021
• John Doe added the label VF to the pull request 06 Aug 2021