fix issue with incorrect input dimensions to model.
fix issue with incorrect input dimensions to model.

sainathadapa/fastai-courses,nik-hil/fastai,matsaleh13/courses,fazzolini/fast_ai,kmclaugh/fastai_courses,yingchi/fastai-notes,yingchi/fastai-notes,nik-hil/fastai,sainathadapa/fastai-courses,kmclaugh/fastai_courses,radekosmulski/courses,fastai/courses,radekosmulski/courses,fazzolini/fast_ai,appleby/fastai-courses,matsaleh13/courses,fastai/courses,appleby/fastai-courses