Kebechet Pipfile Requirements Manager: no Pipfile found in repo

[khebhut]

Kebechet pipfile_requirements manager is installed but no
Pipfile was found in this repository.

    `Pipfile` is required by the pipfile_requirements manager in its
    current configuration (as specified in `.thoth.yaml`).

    Either remove this manager from `.thoth.yaml`, adjust its configuration,
    or update the repository to meet the requirements.

    Reference: see the documentation for
    [pipfile_requirements](https://thoth-station.ninja/docs/developers/kebechet/managers/pipfile_requirements.html).