chore: remove invalid file

scripts/excerpt.js

@@ -1,15 +0,0 @@
-/**
-* Excerpt Helper
-* @description Get the excerpt from a post
-* @example
-*     <%- excerpt(post) %>
-*/
-hexo.extend.helper.register('excerpt', function (post) {
-    var excerpt;
-    if (post.excerpt) {
-        excerpt = post.excerpt.replace(/\<[^\>]+\>/g, '');
-    } else {
-        excerpt = post.content.replace(/\<[^\>]+\>/g, '').substring(0, 200);
-    }
-    return excerpt;
-});