This new API endpoint makes it possible to cancel action runs via the API. Previously this was only natively possible through the UI, the same `CancelRun` func has been reused for this feature.
### Tests for Go changes
- I added test coverage for Go changes...
- [ ] in their respective `*_test.go` for unit tests.
- [x] in the `tests/integration` directory if it involves interactions with a live Forgejo server.
- I ran...
- [x] `make pr-go` before pushing
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## Release notes
<!--URL:https://codeberg.org/forgejo/forgejo-->
- Features
- [PR](https://codeberg.org/forgejo/forgejo/pulls/12957): <!--number 12957 --><!--line 0 --><!--description ZmVhdChhcGkpOiBhZGQgbmV3IGAvcmVwb3Mve293bmVyfS97cmVwb30vYWN0aW9ucy9ydW5zL3tydW5faWR9L2NhbmNlbGAgQVBJIGVuZHBvaW50-->feat(api): add new `/repos/{owner}/{repo}/actions/runs/{run_id}/cancel` API endpoint<!--description-->
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Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/12957
Reviewed-by: limiting-factor <limiting-factor@noreply.codeberg.org>
Reviewed-by: Andreas Ahlenstorf <aahlenst@noreply.codeberg.org>
Reviewed-by: Mathieu Fenniak <mfenniak@noreply.codeberg.org>
