Fixed Last.fm URL (mmistakes#540)

lastfm.com/user... results in a server error, last.fm/user... is the correct URL.

_includes/author-profile.html

@@ -65,7 +65,7 @@ <h3 class="author__name">{{ author.name }}</h3>
         <li><a href="https://www.stackoverflow.com/users/{{ author.stackoverflow }}"><i class="fa fa-fw fa-stack-overflow" aria-hidden="true"></i> Stackoverflow</a></li>
       {% endif %}
       {% if author.lastfm %}
-        <li><a href="https://lastfm.com/user/{{ author.lastfm }}"><i class="fa fa-fw fa-lastfm-square" aria-hidden="true"></i> Last.fm</a></li>
+        <li><a href="https://last.fm/user/{{ author.lastfm }}"><i class="fa fa-fw fa-lastfm-square" aria-hidden="true"></i> Last.fm</a></li>
       {% endif %}
       {% if author.dribbble %}
         <li><a href="https://dribbble.com/{{ author.dribbble }}"><i class="fa fa-fw fa-dribbble" aria-hidden="true"></i> Dribbble</a></li>