Remove unused datetime import and simplify super() call

doi2dataset.py

@@ -26,7 +26,6 @@ import unicodedata
 import warnings  # TODO: Remove once the warning is stripped from idutils
 from collections.abc import Sequence
 from dataclasses import dataclass, field
-from datetime import datetime
 from enum import Enum
 from functools import reduce
 from pathlib import Path
@@ -466,7 +465,7 @@ class Config:
             Config: The singleton instance.
         """
         if cls._instance is None:
-            cls._instance = super(Config, cls).__new__(cls)
+            cls._instance = super().__new__(cls)
         return cls._instance
 
     @classmethod
@@ -1791,8 +1790,7 @@ def main():
             console.print(f"{ICONS['info']} Exposing contact email <{args.contact_mail}> to API services.\n", style="info")
 
         # Process DOIs and track time
-        start_time = datetime.now()
-        results = process_doi_batch(
+        process_doi_batch(
             dois=dois,
             output_dir=output_dir,
             depositor=args.depositor,