Update types for nano.request

[jseminck]

Overview

I updated the type for the request function which currently looks incorrect. The request function is documented correctly in the readme though: https://github.com/apache/couchdb-nano#nanorequestopts-callback

A type for RequestOptions already existed so I re-used that.

Testing recommendations

I tested this change in my local development environment by changing the code in the node_modules folder.

GitHub issue number

I considered raising an issue first to question whether this change is needed or not, but as the change is so minor then I decided creating a PR was easier.

Checklist

• [x] Code is written and works correctly;
• [ ] Changes are covered by tests;
• [ ] Documentation reflects the changes;