Change max line length to 100.
Change max line length to 100.

As per Astropy Coordination Meeting 2019.
aleksandr-bakanov/astropy,mhvk/astropy,StuartLittlefair/astropy,astropy/astropy,lpsinger/astropy,astropy/astropy,dhomeier/astropy,larrybradley/astropy,lpsinger/astropy,saimn/astropy,pllim/astropy,mhvk/astropy,saimn/astropy,dhomeier/astropy,pllim/astropy,mhvk/astropy,saimn/astropy,StuartLittlefair/astropy,saimn/astropy,aleksandr-bakanov/astropy,lpsinger/astropy,mhvk/astropy,astropy/astropy,lpsinger/astropy,dhomeier/astropy,dhomeier/astropy,dhomeier/astropy,StuartLittlefair/astropy,astropy/astropy,lpsinger/astropy,pllim/astropy,larrybradley/astropy,pllim/astropy,StuartLittlefair/astropy,larrybradley/astropy,aleksandr-bakanov/astropy,larrybradley/astropy,astropy/astropy,larrybradley/astropy,mhvk/astropy,pllim/astropy,StuartLittlefair/astropy,saimn/astropy,aleksandr-bakanov/astropy