Update cython version
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larrybradley/astropy,larrybradley/astropy,pllim/astropy,StuartLittlefair/astropy,mhvk/astropy,pllim/astropy,astropy/astropy,StuartLittlefair/astropy,lpsinger/astropy,StuartLittlefair/astropy,lpsinger/astropy,astropy/astropy,pllim/astropy,astropy/astropy,lpsinger/astropy,larrybradley/astropy,mhvk/astropy,mhvk/astropy,larrybradley/astropy,pllim/astropy,mhvk/astropy,pllim/astropy,mhvk/astropy,StuartLittlefair/astropy,StuartLittlefair/astropy,larrybradley/astropy,astropy/astropy,lpsinger/astropy,astropy/astropy,lpsinger/astropy