deps.dev API as an option for PyPI requirements

[cuixq]

deps.dev API is going to support PyPI requirements soon and we should provide an option for transitivedependency enricher and guided remediation to use deps.dev as the backend for requirements.

[cuixq]

Currently blocked by deps.dev api.proto not being updated with PyPI requirements.

Once the proto is updated, we need to update APIClient so PyPI requirements are supported in depsdev client.

[cuixq]

deps.dev changes:

• api: update proto documentation deps.dev#330
• api: regenerate Go client code for v3 and v3alpha APIs deps.dev#331
• util/resolve: add support for PyPI requirements in API client deps.dev#332