chore: upgrade go-git to v5.19.2 to address CVE-2026-71556, CVE-2026-71557 - #21

Bugbot Analysis Progress (3m 57s elapsed)

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Final Result: Bugbot completed review - no issues found! ✅

Request ID: serverGenReqId_fb2806ac-9935-4120-a573-e1e7f5646017