feat: add params to request_pin

[Justintime50]

Description

Adds params to request_pin ensuring users can pass easypost_details to the call.

Testing

Updated test to accept new param.

Pull Request Type

Please select the option(s) that are relevant to this PR.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Improvement (fixing a typo, updating readme, renaming a variable name, etc)