pdf-engine is in format.pandoc not metadata

Author: cderv

src/command/render/filters.ts

@@ -838,7 +838,7 @@ function citeMethod(options: PandocOptions): CiteMethod | null {
 
 function pdfEngine(options: PandocOptions): string {
   const pdfEngine = options.flags?.pdfEngine ||
-    options.metadata?.[kPdfEngine] as string ||
+    options.format.pandoc?.[kPdfEngine] as string ||
     "pdflatex";
   return pdfEngine;
 }