allow non-latex intermediaries for pdf generation (#381)

Co-authored-by: Jessica Tegner <jessica@jessicategner.com>

Author: ashi-agrawal

pypandoc/__init__.py

@@ -339,8 +339,7 @@ def _validate_formats(format, to, outputfile):
         )
 
     if base_to_format == "pdf":
-        # pdf formats needs to actually have a to format of latex and a
-        # filename with an ending pf .pdf
+        # pdf formats need a filename with an ending of .pdf
         if isinstance(outputfile, str):
             if outputfile[-4:] != ".pdf":
                 raise RuntimeError(
@@ -351,11 +350,9 @@ def _validate_formats(format, to, outputfile):
                 raise RuntimeError(
                     'PDF output needs an outputfile with ".pdf" as a fileending.'
                 )
-        # to is not allowed to contain pdf, but must point to latex
         # it's also not allowed to contain extensions according to the docs
         if to != base_to_format:
             raise RuntimeError("PDF output can't contain any extensions: %s" % to)
-        to = "latex"
 
     return format, to