Fix: Update Requester.verify typing to support TLS CA certificate paths

[JannikSt]

Summary

Updated the type annotation for the verify parameter in the Requester class to support both boolean values and string paths to CA certificates (Union[bool, str]). This aligns with the Python requests library's verification parameter and enables proper mTLS setup with custom CA certificates as documented in Nomad's TLS configuration guide.

Details

• Changed verify parameter type from bool to Union[bool, str]
• Maintains backward compatibility with boolean values
• Enables specifying custom CA certificate paths for TLS verification
• Follows the same pattern as the requests library's verify parameter