Fix MANIFEST to mention _websocket extension
Fix MANIFEST to mention _websocket extension

vasylbo/aiohttp,panda73111/aiohttp,moden-py/aiohttp,decentfox/aiohttp,playpauseandstop/aiohttp,alexsdutton/aiohttp,jashandeep-sohi/aiohttp,z2v/aiohttp,AraHaanOrg/aiohttp,vaskalas/aiohttp,jashandeep-sohi/aiohttp,decentfox/aiohttp,pathcl/aiohttp,jojurajan/aiohttp,rutsky/aiohttp,morgan-del/aiohttp,vaskalas/aiohttp,AraHaanOrg/aiohttp,jettify/aiohttp,iksteen/aiohttp,panda73111/aiohttp,avanov/aiohttp,mind1master/aiohttp,KeepSafe/aiohttp,noodle-learns-programming/aiohttp,alex-eri/aiohttp-1,hellysmile/aiohttp,alexsdutton/aiohttp,KeepSafe/aiohttp,jettify/aiohttp,rutsky/aiohttp,arthurdarcet/aiohttp,juliatem/aiohttp,Insoleet/aiohttp,mind1master/aiohttp,esaezgil/aiohttp,sterwill/aiohttp,esaezgil/aiohttp,esaezgil/aiohttp,panda73111/aiohttp,pfreixes/aiohttp,vedun/aiohttp,elastic-coders/aiohttp,moden-py/aiohttp,z2v/aiohttp,decentfox/aiohttp,singulared/aiohttp,jojurajan/aiohttp,rutsky/aiohttp,AlexLisovoy/aiohttp,flying-sheep/aiohttp,KeepSafe/aiohttp,jashandeep-sohi/aiohttp,Srogozins/aiohttp,juliatem/aiohttp,singulared/aiohttp,danielnelson/aiohttp,alex-eri/aiohttp-1,z2v/aiohttp,singulared/aiohttp,alunduil/aiohttp,elastic-coders/aiohttp,andyaguiar/aiohttp,alex-eri/aiohttp-1,moden-py/aiohttp,jettify/aiohttp,AlexLisovoy/aiohttp,vaskalas/aiohttp,hellysmile/aiohttp,elastic-coders/aiohttp,Eyepea/aiohttp,arthurdarcet/aiohttp,mind1master/aiohttp,arthurdarcet/aiohttp,iksteen/aiohttp,pfreixes/aiohttp