The turtleart-activity builds failed with the error:

error in Turtle Art setup command: 'package_data' must be a dictionary
mapping package names to lists of string wildcard patterns
Error: module turtleblocks: Child process exited with code 1

According to Python 3.9's Writing the Setup Script document - Installing
Additional Files [1], setup()'s option "package_data" should be replaced
as "data_files" for setuptools.

[1] https://docs.python.org/3.9/distutils/setupscript.html#installing-additional-files

Fixes: 1000384 ("Replace deprecated distutils with setuptools")