Hv4gha

* Adds testing and support for Python 3.12 (21)

* Updates (slightly) vulnerable pyca/cryptography dependency (16)

* Opens up pyca/cryptography version requirement (6)
* Replaces unsupported datetime.strftime("%s") (9)
* Improved testing:
* Tests using both constrained and unconstrained dependencies (7)
* Adds pytest tests for helper functions (8, 12)

* Provides more detailed API error exceptions (3)
* Uses Pydantic to type check API responses (4)

* Updates (slightly) vulnerable pyca/cryptography dependency (2)

Initial release of this Python library, which helps you use HashiCorp Vault to manage a GitHub App's private RSA key.