old_contents: test_os = [ "ubuntu-20.04" ]
  test_python = [ "3.9" ]
  test_container = test_os
  
new_contents: test_requires = []
  run_requires = []
  install_requires = []
  setup_requires = []
  dev_requires = [
      "pymakehelper",
      "pydmt",
  ]
  
  
  test_os = [ "ubuntu-20.04" ]
  test_python = [ "3.9" ]
  test_container = test_os
  
subject: build it