csv_metadata_quality/check.py: More date formats

We should also allow ISO 8601 extended in combined date and time
format. DSpace does not have a problem with dates in this format
and I have found some metadata that uses this date format.

For example: 2020-08-31T11:04:56Z

See: https://en.wikipedia.org/wiki/ISO_8601

csv_metadata_quality/check.py

@@ -135,6 +135,14 @@ def date(field, field_name):
         # Check if date is valid YYYY-MM-DD format
         datetime.strptime(field, "%Y-%m-%d")
 
+        return field
+    except ValueError:
+        pass
+
+    try:
+        # Check if date is valid YYYY-MM-DDTHH:MM:SSZ format
+        datetime.strptime(field, "%Y-%m-%dT%H:%M:%SZ")
+
         return field
     except ValueError:
         print(f"Invalid date ({field_name}): {field}")