fix(node-server): API class type name correction

[bc-peng]

Description

The current API type definition (getRecordings) does not match with the actual implementation (getRecording). https://github.com/Netflix/pollyjs/blob/cbca602a5a446da46a4a2834f893670b8c577880/packages/%40pollyjs/node-server/src/api.js#L18

Motivation and Context

Correct the name so that we can avoid Typescript's compiler error.

TS2551: Property 'getRecording' does not exist on type 'API'. Did you mean 'getRecordings'?

Types of Changes

• [x] 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 change)

Checklist

• [ ] I have added tests to cover my changes.
• [ ] My change requires a change to the documentation.
• [ ] I have updated the documentation accordingly.
• [x] My code follows the code style of this project.
• [x] My commits and the title of this PR follow the Conventional Commits Specification.
• [x] I have read the contributing guidelines.

[bc-peng]

Closing now after a long period of silence.