workflows/labels: fix merge conflict label (#419836)

                const pull_number = item.number

                const issue_number = item.number

                // The search result is of a format that works for both issues and pull requests and thus

                // does not have all fields of a full pull_request response. Notably, it is missing `head.sha`,

                // which we need to fetch the workflow run below. This field is already available non-search sources.

                // This API request is also important for the merge-conflict label, because it triggers the

                // This API request is important for the merge-conflict label, because it triggers the

                // creation of a new test merge commit. This is needed to actually determine the state of a PR.

                const pull_request = item.head ? item : (await github.rest.pulls.get({

                const pull_request = (await github.rest.pulls.get({

                  ...context.repo,

                  pull_number

                })).data