perf: async load icons

wowchemy/layouts/partials/site_head.html

@@ -85,9 +85,9 @@
   {{ else }}
     {{ $scr.Set "use_cdn" 1 }}
     {{ if site.Params.icon.pack.ai }}
-      {{ printf "<link rel=\"stylesheet\" href=\"%s\" integrity=\"%s\" crossorigin=\"anonymous\">" (printf $css.academicons.url $css.academicons.version) $css.academicons.sri | safeHTML }}
+      {{ printf "<link rel=\"stylesheet\" href=\"%s\" integrity=\"%s\" crossorigin=\"anonymous\" media=\"print\" onload=\"this.media='all'\">" (printf $css.academicons.url $css.academicons.version) $css.academicons.sri | safeHTML }}
     {{ end }}
-    {{ printf "<link rel=\"stylesheet\" href=\"%s\" integrity=\"%s\" crossorigin=\"anonymous\">" (printf $css.fontAwesome.url $css.fontAwesome.version) $css.fontAwesome.sri | safeHTML }}
+    {{ printf "<link rel=\"stylesheet\" href=\"%s\" integrity=\"%s\" crossorigin=\"anonymous\" media=\"print\" onload=\"this.media='all'\">" (printf $css.fontAwesome.url $css.fontAwesome.version) $css.fontAwesome.sri | safeHTML }}
 
     {{/* Workaround `.HasShortcode "gallery"` not parsing page resources (widget page sections) */}}
     {{ $has_gallery := false }}