Add type annotation for dev system tests

[amoghrajesh]

Fixes https://github.com/apache/airflow/actions/runs/16650671910/job/47123366287

dev/system_tests/update_issue_status.py:157: error: Need type annotation for "issue"  [var-annotated]
        for issue in issues[start_from : start_from + max_issues]:
        ^
Found 1 error in 1 file (checked 132 source files)

Cos of

< PyGithub==2.6.1
---
> PyGithub==2.7.0

---

^ Add meaningful description above
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In case of fundamental code changes, an Airflow Improvement Proposal (AIP) is needed.
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[github-actions]

Backport successfully created: v3-0-test

Status	Branch	Result
✅	v3-0-test