remove download_url from setup script as this will quickly get outdated and is easily forgotten to update

Author: mathialo

setup.py

@@ -14,7 +14,6 @@
       long_description=long_description,
       long_description_content_type="text/markdown",
       url="https://github.com/mathialo/bython",
-      download_url="https://github.com/mathialo/bython/archive/v0.8.tar.gz",
       scripts=["scripts/by2py", "scripts/bython", "scripts/py2by"],
       data_files=[("man/man1", ["etc/bython.1", "etc/py2by.1", "etc/by2py.1"])],
       packages=["bython"],