chore: Improve stdout newline handling

Always strip all newlines of the end of all entries, and then add
a single newline back between entries.

papis_extract/exporter.py

@@ -26,7 +26,7 @@ def to_stdout(
     """
     output: str = formatter(document, annotations)
     if output:
-        print(output.rstrip("\n"))
+        print("{output}\n".format(output=output.rstrip("\n")))
 
 
 def to_notes(