deprecation warning for pypi2deb

[Rolf Leggewie]

$ pypi2debian --help
/usr/bin/pypi2debian:63: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
  def run(self):
/usr/bin/pypi2debian:101: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
  def worker(self):
/usr/bin/pypi2debian:171: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
  def build_src_worker(self):
/usr/bin/pypi2debian:191: DeprecationWarning: "@coroutine" decorator is deprecated since Python 3.8, use "async def" instead
  def build_bin_worker(self):
usage: pypi2debian [OPTIONS]
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