Bump onboard package to 0.6.2 with updates

[amrit110]

This pull request updates several dependencies in both pyproject.toml and aieng-eval-agents/pyproject.toml to address recent security vulnerabilities (CVEs) and ensure the project uses secure, patched versions of its libraries.

Dependency security updates:

• Upgraded gradio to version >=6.7.0 in aieng-eval-agents/pyproject.toml to address multiple CVEs (CVE-2026-28414, CVE-2026-27167, CVE-2026-28416, CVE-2026-28415) that were fixed in versions 6.6.0–6.7.0.
• Upgraded pypdf to version >=6.7.5 in both pyproject.toml and aieng-eval-agents/pyproject.toml to fix CVE-2026-28804 (ASCIIHexDecode DoS vulnerability). [1] [2]
• Upgraded authlib to version >=1.6.7 in pyproject.toml to fix CVE-2026-28802 (alg:none JWT bypass vulnerability).

Development dependency update:

• Upgraded aieng-platform-onboard to version >=0.6.2 in the development dependencies group in pyproject.toml.