Update dependency anchor-js to v5 (#98)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

_includes/footer.html

@@ -9,7 +9,7 @@
 
 </footer>
 {% if site.enable_anchorjs %}<!-- AnchorJS -->
-<script src="https://cdnjs.cloudflare.com/ajax/libs/anchor-js/4.3.1/anchor.min.js"></script>
+<script src="https://cdnjs.cloudflare.com/ajax/libs/anchor-js/5.0.0/anchor.min.js"></script>
 <script>
     anchors.options.visible = 'always';
     anchors.add('article h1, article h2, article h3, article h4, article h5, article h6');