Used nbconverter template is deprecated now and throws an error

[banderlog]

When I am trying to run notedown in a fresh virtualenv it drops jinja error:

./venv/bin/notedown tmp.ipynb --to markdown --strip > output.md
Traceback (most recent call last):
  File "./venv/bin/notedown", line 8, in <module>
    sys.exit(app())
  File "/home/bkaba/SoftServe/hrm_translation/PD/notebooks/venv/lib/python3.8/site-packages/notedown/main.py", line 312, in app
    main(args, help=parser.format_help())
  File "/home/bkaba/SoftServe/hrm_translation/PD/notebooks/venv/lib/python3.8/site-packages/notedown/main.py", line 301, in main
    writer.write(notebook, unicode_std_stream('stdout'))
  File "/home/bkaba/SoftServe/hrm_translation/PD/notebooks/venv/lib/python3.8/site-packages/nbformat/v4/rwbase.py", line 124, in write
    nbs = self.writes(nb, **kwargs)
  File "/home/bkaba/SoftServe/hrm_translation/PD/notebooks/venv/lib/python3.8/site-packages/notedown/notedown.py", line 434, in writes
    body, resources = self.exporter.from_notebook_node(notebook)
  File "/home/bkaba/SoftServe/hrm_translation/PD/notebooks/venv/lib/python3.8/site-packages/nbconvert/exporters/templateexporter.py", line 384, in from_notebook_node
    output = self.template.render(nb=nb_copy, resources=resources)
  File "/home/bkaba/SoftServe/hrm_translation/PD/notebooks/venv/lib/python3.8/site-packages/jinja2/environment.py", line 1090, in render
    self.environment.handle_exception()
  File "/home/bkaba/SoftServe/hrm_translation/PD/notebooks/venv/lib/python3.8/site-packages/jinja2/environment.py", line 832, in handle_exception
    reraise(*rewrite_traceback_stack(source=source))
  File "/home/bkaba/SoftServe/hrm_translation/PD/notebooks/venv/lib/python3.8/site-packages/jinja2/_compat.py", line 28, in reraise
    raise value.with_traceback(tb)
  File "/home/bkaba/SoftServe/hrm_translation/PD/notebooks/venv/lib/python3.8/site-packages/notedown/templates/markdown.tpl", line 1, in top-level template code
    {% extends 'display_priority.tpl' %}
  File "/home/bkaba/.local/share/jupyter/nbconvert/templates/compatibility/display_priority.tpl", line 2, in top-level template code
    {%- extends 'display_priority.j2' -%}
jinja2.exceptions.TemplateNotFound: display_priority.j2

Linked to this: jupyter/nbconvert#1369