Adjust test fixture

Author: ralfhandl

tests/md2html/fixtures/basic-new.html

@@ -10,7 +10,7 @@
 <p>Definition of Foo.</p>
 </section></section><section><h1>Another Heading 2</h1>
 <p>Text for second section</p>
-<p><a href="https://learn.openapis.org/examples/foo.yaml">Relative link to example</a></p>
+<p><a href="https://learn.openapis.org/examples/foo.html">Relative link to example</a></p>
 <p><a href="https://github.com/OAI/OpenAPI-Specification/tree/main/something/else">Relative link to something else</a></p>
 <section><h2>Heading 3</h2>
 <p>Text for first subsection</p>