chore: cascading pr action input is close, not close-merge (#9175)

Without this argument, the action leaves pull requests open when running end-to-end tests and they need to be manually cleaned up.

## Testing

After this pull request is merged, o

- open a test pull requst
- set the `run-end-to-end-test` label
- after it completes, close the pull request
- verify the pull requests opened in https://code.forgejo.org/actions/setup-forgejo and https://code.forgejo.org/forgejo/end-to-end were closed

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/9175
Reviewed-by: Michael Kriese <michael.kriese@gmx.de>
Co-authored-by: Earl Warren <contact@earl-warren.org>
Co-committed-by: Earl Warren <contact@earl-warren.org>

.forgejo/workflows/cascade-setup-end-to-end.yml

@@ -53,5 +53,5 @@ jobs:
           destination-repo: forgejo/end-to-end
           destination-branch: main
           destination-token: ${{ secrets.END_TO_END_CASCADING_PR_DESTINATION }}
-          close-merge: true
+          close: true
           update: .forgejo/cascading-pr-end-to-end