unpaper: don't use universal_newlines=True

There's no specific reason to do this. We can log binary output equally
 well.

src/ocrmypdf/_exec/unpaper.py

@@ -83,7 +83,6 @@ def run(input_file, output_file, dpi, mode_args):
             args_unpaper,
             close_fds=True,
             check=True,
-            universal_newlines=True,
             stderr=STDOUT,  # unpaper writes logging output to stdout and stderr
             stdout=PIPE,  # and cannot send file output to stdout
             cwd=tmpdir,