A ZoltarConnection object as returned by new_connection()
project_url
URL of a project in zoltar_connection's projects
truth_csv_file
A CSV file as documented at https://docs.zoltardata.com/fileformats/#truth-data-format-csv
issued_at
optional datetime to use for the uploaded truth forecasts' issued_at value in ISO 8601 format. NB:
it must include timezone information. (the default issued_at is the time of upload.) the value must obey the
constraints documented at https://docs.zoltardata.com/forecastversions/#forecast-version-rules