replace deprecated pkg_resources with importlib.resources

[danielfromearth]

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📚 Documentation preview 📚: https://earthaccess--452.org.readthedocs.build/en/452/

[chuckwondo]

@danielfromearth, importlib.resources.files was added in 3.9, which is why the build on 3.8 is failing. See https://docs.python.org/3/library/importlib.resources.html#importlib.resources.files

To support earlier versions of Python, you should use importlib_resources (an external package), which acts as a "backport". See https://importlib-resources.readthedocs.io/en/latest/migration.html

[danielfromearth]

This PR has been superseded by #497