setup.py: fix ResourceWarning
setup.py: fix ResourceWarning

jashandeep-sohi/asyncio,haypo/trollius,jashandeep-sohi/asyncio,gsb-eng/asyncio,haypo/trollius,vxgmichel/asyncio,ajdavis/asyncio,haypo/trollius,Martiusweb/asyncio,ajdavis/asyncio,manipopopo/asyncio,ajdavis/asyncio,manipopopo/asyncio,vxgmichel/asyncio,fallen/asyncio,Martiusweb/asyncio,1st1/asyncio,1st1/asyncio,gvanrossum/asyncio,fallen/asyncio,jashandeep-sohi/asyncio,gsb-eng/asyncio,gvanrossum/asyncio,1st1/asyncio,Martiusweb/asyncio,vxgmichel/asyncio,gvanrossum/asyncio,gsb-eng/asyncio,manipopopo/asyncio,fallen/asyncio