chore: 隐藏选修课

src/pages/learn/course.vue

@@ -87,10 +87,10 @@ export default {
               val: '1',
               name: this.$t('pages.learn.course.mustLearn')
             },
-            {
-              val: '2',
-              name: this.$t('pages.learn.course.changeLearn')
-            },
+            // {
+            //   val: '2',
+            //   name: this.$t('pages.learn.course.changeLearn')
+            // },
             {
               val: '3',
               name: this.$t('pages.learn.course.repeatLearn')