Update to jekyll 4 (modernization)

blog/repaircafe.html

@@ -85,7 +85,7 @@ show_mobile_large_logo: true
 
             <header class="post-header">
                 <h2 class="post-title">
-                    <a href="{{ post.url | prepend: site.baseurl }}">
+                    <a href="{{ post.url | relative_url }}">
                         {{ post.title }}
                     </a>
                 </h2>
@@ -99,7 +99,7 @@ show_mobile_large_logo: true
                 {% assign wordcount = post.content | number_of_words %}
                 {% if wordcount > 200 %}
                 <p>
-                    <a class="btn btn-default" href="{{ post.url | prepend: site.baseurl }}" role="button">
+                    <a class="btn btn-default" href="{{ post.url | relative_url }}" role="button">
                         &gt; Weiterlesen
                     </a>
                 </p>