Remove `type` and `language` attributes of `script` element (#2021)

The `type` attribute is not needed when the content is JavaScript,
and the `language` attribute is deprecated.

Signed-off-by: Kévin Commaille <zecakeh@tedomum.fr>

changelogs/internal/newsfragments/2021.clarification

@@ -0,0 +1 @@
+Remove `type` and `language` attributes of `script` element.

layouts/partials/hooks/body-end.html

@@ -7,4 +7,4 @@
 
 */}}
 {{ $toc := resources.Get "js/toc.js" -}}
-<script defer language="javascript" type="text/javascript"  src="{{ $toc.RelPermalink }}"></script>
+<script defer src="{{ $toc.RelPermalink }}"></script>