Add webhook events for access requests
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What does this MR do and why?
Add webhook events for access requests
Related to gitlab-community/meta#692 (closed)
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How to set up and validate locally
- Create a group webhook (ensure you have the feature available first)
- Request access to the group with another user
- Reject the access request
- Request access to the group with another user
- Approve the access request
- Ensure you have received a call for each of these actions with the appropriate event_name
Edited  by Niklas van Schrick
