tpl/tmplimpl: Add MIME type to embedded JS

So they get minified correctly.

See #5042

tpl/tplimpl/embedded/templates/google_analytics_async.html

@@ -1,7 +1,7 @@
 {{- $pc := .Site.Config.Privacy.GoogleAnalytics -}}
 {{- if not $pc.Disable -}}
 {{ with .Site.GoogleAnalytics }}
-<script>
+<script type="application/javascript">
 {{ template "__ga_js_set_doNotTrack" $ }}
 if (!doNotTrack) {
 	window.ga=window.ga||function(){(ga.q=ga.q||[]).push(arguments)};ga.l=+new Date;