security/py-pgpy: Update 0.5.3 => 0.6.0, fix with python 3.13+

Changelogs:
https://github.com/SecurityInnovation/PGPy/releases/tag/v0.5.4
https://github.com/SecurityInnovation/PGPy/releases/tag/v0.6.0

Commit log:
https://github.com/SecurityInnovation/PGPy/compare/v0.5.3...v0.6.0

PR: 298667
Approved by: contact@evilham.com (maintainer, timeout > 2 weeks)
Sponsored by: UNIS Labs (vvd)
Co-authored-by: Vladimir Druzenko <vvd@FreeBSD.org>