TST: add value to pytest.ini for pytest6 compatibility
TST: add value to pytest.ini for pytest6 compatibility

jakirkham/numpy,mhvk/numpy,mhvk/numpy,grlee77/numpy,madphysicist/numpy,madphysicist/numpy,grlee77/numpy,simongibbons/numpy,charris/numpy,numpy/numpy,numpy/numpy,pbrod/numpy,pbrod/numpy,seberg/numpy,simongibbons/numpy,grlee77/numpy,mattip/numpy,madphysicist/numpy,WarrenWeckesser/numpy,seberg/numpy,WarrenWeckesser/numpy,mhvk/numpy,grlee77/numpy,mhvk/numpy,pbrod/numpy,anntzer/numpy,jakirkham/numpy,jakirkham/numpy,grlee77/numpy,endolith/numpy,anntzer/numpy,WarrenWeckesser/numpy,jakirkham/numpy,anntzer/numpy,pbrod/numpy,mattip/numpy,pdebuyl/numpy,jakirkham/numpy,madphysicist/numpy,pdebuyl/numpy,rgommers/numpy,mattip/numpy,seberg/numpy,pdebuyl/numpy,numpy/numpy,charris/numpy,rgommers/numpy,endolith/numpy,abalkin/numpy,endolith/numpy,WarrenWeckesser/numpy,pbrod/numpy,simongibbons/numpy,madphysicist/numpy,WarrenWeckesser/numpy,mhvk/numpy,pdebuyl/numpy,charris/numpy,simongibbons/numpy,endolith/numpy,charris/numpy,simongibbons/numpy,numpy/numpy,mattip/numpy,rgommers/numpy,seberg/numpy,abalkin/numpy,anntzer/numpy,abalkin/numpy,rgommers/numpy