Remove duplicate entries from atest/requirements.txt
# External Python modules required by acceptance tests.
# See atest/README.rst for more information.
-docutils >= 0.9; platform_python_implementation != 'IronPython' # https://github.com/IronLanguages/ironpython2/issues/113
-pygments
-pyyaml; platform_python_implementation != 'Jython'
-pyyaml==5.2; platform_python_implementation == 'Jython'
enum34; python_version < '3.0'
pillow; platform_system == 'Windows'
