Missing driving_source for ERA5 in driving_source_id

[huard]

  "ERA5": {
        "driving_institution_id": [
            "ECMWF"
        ],
        "driving_source_id": "ERA5",
        "driving_experiment_id": [
            "evaluation"
        ]

All other items have a driving_source attribute.

[larsbuntemeyer]

Thanks @huard for pointing this out. The driving_source global attribute is not a required global attribute and is inherited from the CMIP6 CV simply for convenience. But i think it's a good idea to add an entry for ERA5.

Note to myself: keep the json up to date here! The ERA5 entry was only created dynamically during the table creation...