Typst template: fix 3.8 regression in which links disappear.

A template change in 3.8 added a show rule for links which
causes them to disappear except in special cases.

This change fixes the problem.

Closes #11194.

test/writer.typst

@@ -91,6 +91,8 @@
   show link: this => {
     if filecolor != none and type(this.dest) == label {
       text(this, fill: rgb(content-to-string(filecolor)))
+    } else {
+      text(this)
     }
   }