Fix highlighting for pub keyword

[jaschdoc]

pub is marked as a keyword in the spec but it seems it doesn't recognize it as a keyword. The output for

pub def map(f: a -> b, t: t[a, r]): t[b, r] \ { Read(r), Write(r) }

is

pub <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">map</span></span>(f: a -&gt; b, t: t[a, r]): t[b, r] \ { Read(r), Write(r) }

but should be

<span class="hljs-keyword">pub</span> <span class="hljs-function"><span class="hljs-keyword">def</span> <span class="hljs-title">map</span></span>(f: a -&gt; b, t: t[a, r]): t[b, r] \ { Read(r), Write(r) }

[jaschdoc]

It works on doc.flix.dev so no problem. Weird why the test does not output it though.