Add invalid keyword to PowerStretch
Add invalid keyword to PowerStretch

dhomeier/astropy,astropy/astropy,aleksandr-bakanov/astropy,StuartLittlefair/astropy,aleksandr-bakanov/astropy,saimn/astropy,mhvk/astropy,mhvk/astropy,larrybradley/astropy,lpsinger/astropy,larrybradley/astropy,lpsinger/astropy,StuartLittlefair/astropy,dhomeier/astropy,saimn/astropy,larrybradley/astropy,dhomeier/astropy,aleksandr-bakanov/astropy,dhomeier/astropy,aleksandr-bakanov/astropy,StuartLittlefair/astropy,StuartLittlefair/astropy,saimn/astropy,pllim/astropy,astropy/astropy,astropy/astropy,saimn/astropy,larrybradley/astropy,pllim/astropy,lpsinger/astropy,lpsinger/astropy,lpsinger/astropy,pllim/astropy,larrybradley/astropy,mhvk/astropy,mhvk/astropy,pllim/astropy,saimn/astropy,astropy/astropy,StuartLittlefair/astropy,pllim/astropy,astropy/astropy,mhvk/astropy,dhomeier/astropy