docs: Fix external link indicator on Chrome

Author: pawamoy

docs/css/mkdocstrings.css

@@ -9,6 +9,7 @@ a.external::after,
 a.autorefs-external::after {
   /* https://primer.style/octicons/arrow-up-right-24 */
   mask-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M18.25 15.5a.75.75 0 00.75-.75v-9a.75.75 0 00-.75-.75h-9a.75.75 0 000 1.5h7.19L6.22 16.72a.75.75 0 101.06 1.06L17.5 7.56v7.19c0 .414.336.75.75.75z"></path></svg>');
+  -webkit-mask-image: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24"><path d="M18.25 15.5a.75.75 0 00.75-.75v-9a.75.75 0 00-.75-.75h-9a.75.75 0 000 1.5h7.19L6.22 16.72a.75.75 0 101.06 1.06L17.5 7.56v7.19c0 .414.336.75.75.75z"></path></svg>');
   content: ' ';
 
   display: inline-block;