[Chore] Migrate from deprecated pdpyras to pagerduty package

[jychp]

Description

The project currently triggers a deprecation warning due to the use of the pdpyras package:

/home/runner/work/cartography-github-action/cartography-github-action/.venv/lib/python3.10/site-packages/pdpyras.py:26: UserWarning: The package "pdpyras" is deprecated and as of 2025-06-20 will no longer receive updates. Please use "pagerduty" instead. Migration guide: https://pagerduty.github.io/python-pagerduty/pdpyras_migration_guide.html

Motivation

• pdpyras is officially deprecated and will no longer receive updates after 2025-06-20.
• To avoid relying on an unmaintained dependency, we should migrate to the new pagerduty package.
• This ensures long-term support, security updates, and compatibility.

Scope

• Replace pdpyras with pagerduty in dependencies.
• Update codebase to use the new package API (see migration guide).
• Adjust tests accordingly.

Checklist

• Update dependencies
• Refactor code to use pagerduty API
• Update / add tests if necessary
• Remove pdpyras from requirements
• Verify no warnings remain in CI

Additional Notes

• Migration guide: https://pagerduty.github.io/python-pagerduty/pdpyras_migration_guide.html