AddSubIssue functions missing

Start by checking how this repository exposes the Octokit REST client and which Octokit version it uses; the report shows that issues.addSubIssue is missing while the latest release documents it. Reproduce the GitHub Actions script from the issue, then verify that the sub-issue call is available and creates the expected link.

Describe the bug
github.rest.issues.addSubIssue is not a function, octokit has the function in the latest release

To Reproduce
Run a github action to create a sub issue:

      - name: Create linked sub-issues from tasklist
        uses: actions/github-script@v7.0.1
        with:
          script: |
            const issueBody = context.payload.issue.body
            const parentIssueNumber = context.payload.issue.number

            // Extract the content between ```[tasklist] and ```
            const matchTasklist = issueBody.match(/```\[tasklist\]([\s\S]*?)```/)
            if (!matchTasklist) {
              core.info('No [tasklist] section found in the issue body.')
              return
            }

            const tasklistContent = matchTasklist[1]
            // Identify lines that match '- [ ] ...'
            const tasks = tasklistContent.match(/^- \[ \] .+/gm) || []

            for (const task of tasks) {
              const title = task.replace(/^- \[ \] /, '').trim()
              const newIssue = await github.rest.issues.create({
                owner: context.repo.owner,
                repo: context.repo.repo,
                title: title,
                body: `Sub-issue of #${parentIssueNumber}`
              })

              // Link the sub issue to the parent issue
              await github.rest.issues.addSubIssue({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: parentIssueNumber,
                sub_issue_id: newIssue.data.id
              })

               // Comment on the parent issue linking the new sub-issue
              await github.rest.issues.createComment({
                owner: context.repo.owner,
                repo: context.repo.repo,
                issue_number: parentIssueNumber,
                body: `Created sub-issue: #${newIssue.data.number} for task: "${title}"`
              })             
            }

Expected behavior
A sub issue should be created based on the inputs

Screenshots

Additional context
Trying to create sub issues based off an issue template and hitting this error