fix: remove warning (#3128)

lm_eval/filters/extraction.py

@@ -141,7 +141,7 @@ class MultiChoiceRegexFilter(RegexFilter):
         """
         regex_pattern: The basic regex pattern to use. If fails to match, we will use the customized match procedure
                         - step 1 : We parse the choices between ([A-Z])s then try to find these choices in the response.
-                        - step 2 : We parse the choice with regex: r'\s*([A-?])', where ? varies by number of choices.
+                        - step 2 : We parse the choice with regex: r's*([A-?])', where ? varies by number of choices.
         group_select: Selects the (group_select)th match from the findall result.
         ignore_case: Ignores the case during step 1 matching
         ignore_punctuation: Remove the punctuation during step 1 matching