[3.12] Explicitly import urllib.error in urllib.robotparser (pythonGH-128737) (python#128794)

Explicitly import `urllib.error` in `urllib.robotparser` (pythonGH-128737)
(cherry picked from commit 53e8942)

Co-authored-by: Bénédikt Tran <[email protected]>

Author: miss-islington

Lib/urllib/robotparser.py

@@ -11,6 +11,7 @@
 """
 
 import collections
+import urllib.error
 import urllib.parse
 import urllib.request