CS2 Match-API: Added Cancel Endpoint

Today, we're rolling out a new feature to facilitate the force-cancellation of matches. When you cancel a live match, the following actions will be taken:

1. All players will be kicked from the server
2. The match will be marked as finished, with the cancel_reason: USER_API_CANCEL
3. A webhooks.match_end_url will be sent to your specified URL.

Check out the endpoint here: https://dathost.net/reference/post_api-0-1-cs2-matches-match-id-cancel