update regex

lm_eval/tasks/mrl/gen/_template

@@ -12,7 +12,7 @@ filter_list:
   - name: strict_match
     filter:
       - function: "regex"
-        regex_pattern: 'best answer(?:\s+is)?(?:\s*:)?\s*([A-B])'
+        regex_pattern: '[Tt]he (?:[Bb]est [Aa]nswer|[Ff]inal [Aa]nswer|[Aa]nswer)[^A-B]*([A-B])|[Aa]nswer\s*:[^A-B]*([A-B])|\\boxed\{([A-B])\}'
         group_select: -1
       - function: take_first
 metric_list: