TST: mark bytes/str issue with Wavelet string properties as knownfail in py3.
TST: mark bytes/str issue with Wavelet string properties as knownfail in py3.

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