Fix: "DeprecationWarning: open_binary is deprecated."

[khaledhosny]

This requires Python 3.9, though, so lets keep open until we drop 3.8 support.

[anthrotype]

the importlib_resources backport should work for python < 3.9 if you really want to fix this now, you'd have to add it to the install_requires but only for python < 3.9