earthobservations/wetterdienst: Add ECCC API

Use direct mapping to get a parameter set for a parameter Rename DwdObservationParameterSet to DwdObservationDataset as well as corresponding columns Merge metadata access into Request Repair CLI and I/O subsystem Add capability to export to Feather- and Parquet-files to I/O subsystem Deprecate support for Python 3.6 Add --reload parameter to wetterdienst service for supporting development Improve spreadsheet export Increase I/O subsystem test coverage Make all DWD observation field names lowercase Make all DWD forecast (mosmix) field names lowercase Add Environment and Climate Change Canada API Rename humanize_parameters to humanize and tidy_data to tid