Remove crossorigin attribute from katex.min.css

Signed-off-by: Danila Fedorin <danila.fedorin@gmail.com>

layouts/partials/head.html

@@ -15,7 +15,7 @@
 
     <!-- External CSS (normalize and KaTeX -->
     {{ partial "defercss.html" (dict "url" .Site.Params.normalizeCssUrl "extra" "") }}
-    {{ partial "defercss.html" (dict "url" .Site.Params.katexCssUrl "extra" "crossorigin=\"anonymous\"") }}
+    {{ partial "defercss.html" (dict "url" .Site.Params.katexCssUrl "extra" "") }}
 
     <!-- Links to other formats (RSS, TOML) -->
     {{ range .AlternativeOutputFormats -}}