Apply suggestions from code review, fix numpy version and relax openslide version
Apply suggestions from code review, fix numpy version and relax openslide version

Co-authored-by: Jaime Rodríguez-Guerra <5eeb9291dcba3f3719fd983e09c1a0c357f0735a@users.noreply.github.com>
ocefpaf/staged-recipes,johanneskoester/staged-recipes,jakirkham/staged-recipes,stuertz/staged-recipes,ocefpaf/staged-recipes,mariusvniekerk/staged-recipes,conda-forge/staged-recipes,goanpeca/staged-recipes,conda-forge/staged-recipes,kwilcox/staged-recipes,stuertz/staged-recipes,goanpeca/staged-recipes,kwilcox/staged-recipes,johanneskoester/staged-recipes,mariusvniekerk/staged-recipes,jakirkham/staged-recipes