Silence punycode warning

src/plugins/syntaxHighlightingPlugin.ts

@@ -73,11 +73,16 @@ export class SyntaxHighlightingPlugin implements DjockeyPlugin {
   }
 
   async setup() {
-    // TODO: monkey-patch console.error here
+    // Some transitive dependencies of myst-parser pin an old version of markdown-it which
+    // imports the deprecated module 'punycode'. It happens to trigger the deprecation
+    // warning here. Silence it for the sake of the users.
+    const err = console.error;
+    console.error = () => {};
     this.djotHighlighter = await createHighlighter({
       langs: [djotTextmateGrammar as unknown as LanguageRegistration],
       themes: [this.themeLight, this.themeDark],
     });
+    console.error = err;
   }
 
   async highlight(text: string, lang: string): Promise<string> {