fix(rpg) use slice not truncatechar for commit ids

truncatechar adds ellipses which is not desirable

rpg/templates/rpg/github_landing.html

@@ -75,7 +75,7 @@ <h2>Vulnerabilities</h2>
       <li>
         <p>
           {% if v.spades %}<strong>{{ v.spades }}♠</strong> for{% endif %}
-          <a href="{{ v.get_absolute_url }}">{{ v.commit_hash|truncatechars:7 }}</a>
+          <a href="{{ v.get_absolute_url }}">{{ v.commit_hash|slice:":7" }}</a>
           —
           {{ v.description }}
           <br />