Fix BBH multichoice config

tasks/bbh/bbh-multichoice.yaml

@@ -1,7 +1,6 @@
 name: 'Big-bench Hard Multichoice'
 type: 'mul'
 path: 'bbh_cot/direct/multichoice'
-module: 'tasks.bbh.task.BBHMultichoice'
 file-pattern:
   test: "**/*.json*"
 micro-batch-size: 8