0.3.8 version is not compatible with Python 2 but installed by pip

[paskino]

I installed nbstripout (thanks!) with pip on python2.7 on ubuntu 18.04.

I got the following error due to different signature of the open function with python 2 and 3.

The problem I'm reporting is with the pip package that does not realise that the latest version 0.3.8 is incompatible with python2.

default: Traceback (most recent call last):
    default:   File "/home/sirfuser/.local/bin/nbstripout", line 8, in <module>
    default:
    default: sys.exit(main())
    default:   File "/home/sirfuser/.local/lib/python2.7/site-packages/nbstripout/_nbstripout.py", line 295, in main
    default:
    default: sys.exit(install(git_config, user=args._global, attrfile=args.attributes))
    default:   File "/home/sirfuser/.local/lib/python2.7/site-packages/nbstripout/_nbstripout.py", line 173, in install
    default:
    default: with open(attrfile, 'a', newline='') as f:
    default: TypeError
    default: :
    default: 'newline' is an invalid keyword argument for this function

[paskino]

To be honest, given that Python2 has been dropped this isn't quite an issue. But it's worth mentioning it in your readme.

[kynan]

Thanks, will add a note that Python 2 is no longer supported.