TST: remove argparse install; already installed.  Fixes Python 2.6 tests.
TST: remove argparse install; already installed.  Fixes Python 2.6 tests.

PyWavelets/pywt,michelp/pywt,grlee77/pywt,michelp/pywt,rgommers/pywt,ThomasA/pywt,ThomasA/pywt,PyWavelets/pywt,kwohlfahrt/pywt,eriol/pywt,kwohlfahrt/pywt,eriol/pywt,aaren/pywt,kwohlfahrt/pywt,rgommers/pywt,ThomasA/pywt,aaren/pywt,rgommers/pywt,aaren/pywt,michelp/pywt,grlee77/pywt,rgommers/pywt,eriol/pywt