Update _includes/poster-list.html

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: Grufoony

_includes/poster-list.html

@@ -2,12 +2,12 @@
 {% for poster in posters %}
 <div class="citation-container">
   <div class="citation">
-    <a href="{{ poster.pdf | relative_url }}" target="_blank" class="citation-image" aria-label="{{ poster.title | default: 'poster link' | regex_strip }}">
+    <a href="{{ poster.pdf | relative_url }}" target="_blank" rel="noopener noreferrer" class="citation-image" aria-label="{{ poster.title | default: 'poster link' | regex_strip }}">
       {% include pdf-preview.html pdf=poster.pdf image=poster.image title=poster.title %}
     </a>
     <div class="citation-text">
       {% include icon.html icon="fa-solid fa-chalkboard" %}
-      <a href="{{ poster.pdf | relative_url }}" target="_blank" class="citation-title">{{ poster.title }}</a>
+      <a href="{{ poster.pdf | relative_url }}" target="_blank" rel="noopener noreferrer" class="citation-title">{{ poster.title }}</a>
       <div class="citation-authors">
         {%- for author in poster.authors -%}
           {%- if author.member -%}