ItemLocateError broken on Python 2

[JustAnotherArchivist]

internetarchive claims Python 2 compatibility, but ItemLocateError (introduced by deb0d91 and first released in 1.9.2) makes use of super(), which is only available in this argument-less form on Python 3.

> python2 -c 'from internetarchive.exceptions import ItemLocateError; ItemLocateError()'
TypeError: super() takes at least 1 argument (0 given)

I haven't checked whether there are any other issues with Python 2 as I uninstalled that after it reached EOL at the beginning of this year.

Credit for finding this goes to @jodizzle.

[JustAnotherArchivist]

Fixed by dropping Python 2 support per #435.