Loosening of types for test frameworks

The only change in this minor patch release is a loosening of types on the CurlInterface, which allows for test frameworks to inject their own CurlInterface implementation - the purpose of this library is to help test endpoints without requiring an internet connection, so this is a vital feature.

What's Changed

• Loosen types for test frameworks by @g105b in #84

Full Changelog: v3.1.0...v3.1.1