Update update_data.py: make the space in error comments optional

Author: wyattscarpenter

mypy/test/update_data.py

@@ -64,7 +64,7 @@ def _iter_fixes(
         fix_lines = []
         for lineno, source_line in enumerate(source_lines, start=1):
             reports = reports_by_line.get((file_path, lineno))
-            comment_match = re.search(r"(?P<indent>\s+)(?P<comment># [EWN]: .+)$", source_line)
+            comment_match = re.search(r"(?P<indent>\s+)(?P<comment># ?[EWN]: .+)$", source_line)
             if comment_match:
                 source_line = source_line[: comment_match.start("indent")]  # strip old comment
             if reports: