🐛Fixed multiple authors for amp (#10253)

no issue

- refs: gscan `GS001-DEPR-AUTHBL`
- the amp page always printed a single author only

core/server/apps/amp/lib/views/amp.hbs

@@ -42,9 +42,7 @@
             <header class="post-header">
                 <h1 class="post-title">{{title}}</h1>
                 <section class="post-meta">
-                    {{#author}}
-                    <p class="author">by <a href="{{url}}">{{name}}</a></p>
-                    {{/author}}
+                    <p class="author">by {{authors}}</p>
                     <time class="post-date" datetime="{{date format="YYYY-MM-DD"}}">{{date format="YYYY-MM-DD"}}</time>
                 </section>
             </header>